A few years ago, the actor Robert Duvall was being interviewed for this paper when, apropos of nothing, he cited Leonard Rossiter as the finest performer he’d ever seen. Four decades after Rossiter’s death, his singular style – manic energy, machine-gun delivery, splenetic intelligence – continues to carry remarkable currency.

Rossiter became a household name in the UK for two 1970s sitcoms, which ran concurrently on BBC One and ITV, but he was also a hugely respected stage actor. Film stardom eluded him, despite regular work with John Schlesinger and Lindsay Anderson and the adoration of Stanley Kubrick. Yet it might have followed: at the time of his death, he was lined up to play the role eventually taken by Tim Curry in Clue.

Born in 1926, Rossiter grew up in the suburbs of Liverpool, the son of a barber-cum-bookie whose sole showbiz connection was sometimes playing golf with George Formby. He won a place to study French and German at university but his father’s death in an air raid in 1944 meant he had to provide for the rest of his family. So he joined an insurance company where he spent the next seven years, some on the next desk to the young Michael Williams.

A girlfriend, Ida, was part of a local amateur dramatics troupe; Rossiter critiqued the actors after rehearsal one evening and Ida challenged him to do better. He rapidly rose through their ranks, then quit his job to join Preston rep aged 27. Then followed a decade of disciplined stints at theatres around the country, as well as bit parts on Z Cars and Play for Today, and in films including Oliver! (as the undertaker, Mr Sowerberry) and Billy Liar (as Shadrack, Billy’s loathed boss).

His belated breakthrough came when he was 41, in Michael Blakemore’s production of The Resistible Rise of Arturo Ui: the first time Brecht’s Chicago-set Third Reich satire had been staged in Britain. As a star vehicle it was unlikely – and ideal.

Bill Paterson: I was a drama student in Glasgow and, by a great bit of luck, was one of a number of the students released to be part of the production. It was my debut, and I found myself as Ui’s gunman. We had two or three weeks to rehearse this absolutely vast show. It wasn’t nearly enough.

But with Len, it felt like he’d done the part before, as if he were just dropping in to do a fresh production and we were just slotting in around him. In fact, he’d just meticulously prepared the text. He was dead letter perfect. I don’t remember him looking at a script at all.

On the opening night, we still hadn’t done a tech rehearsal of the final scene, which involved a huge scaffolding tower moving down the stage. The Citizens theatre has quite a rake, so it could easily have run away with itself and crashed into the stalls killing everybody.

We had a slow first week but after the fairly quiet Saturday matinee the house manager came in to say they were queueing round the block. It was like a dam had burst. The whole city wanted to see it. We’d had a great write up in the Glasgow Herald and the Scotsman, and word of mouth was brilliant.

Tim Preece [later his co-star in Reggie Perrin]: Len’s performance as Arturo was startling, awe-inspiring. I went round backstage to his dressing room afterwards to say how extraordinary it had been, and he wouldn’t have any of that; it was if he’d just made quite a nice stew for supper, that’s all.

Bill Paterson: You could not take your eyes off him. It was like he was plugged into the mains, into the National Grid, he was just sparking. We were in awe of him. He sweated through several shirts in the course of a performance. I remember standing beside him as the poor wardrobe staff tried desperately to change his shirt, wringing wet, during a brief pause.

Don Warrington [later his co-star in Rising Damp]: I saw the play when I was at drama school. I just thought he was absolutely fantastic. The kind of energy he was using was amazing. When I told him that later, he laughed and walked away.

Jonathan Lynn [later his director on Loot]: Sensational performance. I can’t imagine it being played any better.

Alan Strachan [later his director on The Immortal Haydon]: Frightening in its manic energy and often equally savagely funny, this was great acting.

Bill Paterson: It was full-on, non-stop and he gave no time at all to any kind of trivia. There was no sitting around swapping stories telling anecdotes. He wasn’t a hail fellow well met leader of the company, though we had a few nice chats over a cup of tea.

The production runs for another three weeks, then the following year is a smash at the Edinburgh festival, where it opens on the day of the Soviet invasion of Czechoslovakia. Paterson remains with the production; newcomers include Richard Wilson and Steven Berkoff.

Steven Berkoff: His performance was very natural yet it was also a mixture of 50% comic and 50% manic. That’s a terrible, wonderful combination, which Laurence Olivier had too. Len loved the success of the play, and he loved that it enabled him to use all his facilities at once: comedy, mimicry, grotesque, drama, terror and timing.

Some actors have a very strong inner life and a strong visceral power. He did and more: it was as if a live electric wire ran through him. You’d touch him and get a shock. He used that power with great intensity.

He liked talking about sports and played squash to excess. He was always bone thin: face like an eagle, nose like a hawk. Obsessed with being totally dynamic and exploded in performance.

He didn’t suffer fools but I didn’t find that frightening. I found him very affable. No affectation or grandiose ambition. Never talked shop. He loved playing cards after the show – not for high stakes but just to unwind. On Saturday nights a group of us would gather in someone’s flat and play poker nearly all night over coffee and cake.

In 1968, Rossiter has a small role in Stanley Kubrick’s 2001: A Space Odyssey, as a Russian scientist.

Bill Paterson: A gang of us went to see 2001 one afternoon while doing the show. Len might have come too. We were a gang. He had a very good reputation among actors. You wouldn’t have wanted to let him down. Ten years ago I did Waiting for Godot with Brian Cox and we made a pact that we would both completely learn our lines before we started rehearsals. That was a hangover from seeing Len in 1967.

The following year, Arturo Ui moves to the West End, where it cements Rossiter as a star.

Steven Berkoff: I wasn’t in it any more but I took [playwright and screenwriter] Wolf Mankowitz to watch it and then, very proudly, backstage to meet Len. Wolf was terribly impressed: “Mr Rossiter, this is most fantastic performance!” Len said: “Oh, you should have been here at the matinee – the audience was much better.” He couldn’t take a compliment. And he was always very conscious of the crowd, often talking about how they were a bit disappointing.

Rossiter reunites with Courtenay for Dick Clement’s 1968 film, Otley.

Camilla Waterman [nee Rossiter, Leonard’s daughter]: I always quite like watching him as a hitman who’s actually quite nice and friendly.

Dick Clement: He was not an obvious assassin, but he played it beautifully, very low key. That started me off on a very good foot with Len. But he was quite tough to work with because he wasn’t particularly tolerant of people who couldn’t keep up with him.

He played a few times for the cricket team I ran. And we were both Chelsea fans; he lived round the corner from the ground. He had a lively interest in just about everything but he was a real sports nut.

Camilla Waterman: When he wanted to do something, he wanted to be very, very good at it. Squash he had a natural talent for, but he worked hard at it and played up to three times a day.

He was always cross if he found something sporty that he couldn’t do. There was an attempt at windsurfing when we were on holiday in the south of France. He was no good at it. He was really cross and wasn’t going to entertain with windsurfing any more.

I think sport was an outlet as well. I’ve certainly never heard that he suffered from stage fright. His adrenaline would have been channelled into the performance. He wasn’t the sort to lie on a sunbed for two weeks.

He was a perfectionist. Had he not become an actor, I’m sure he’d have taken the same attitude to insurance. I can remember him sitting on the sofa, talking into the air, going over his lines again and again and again.

Robin Askwith: I got to know him through squash, though he was a far superior player. But if we were playing in front of a crowd, he’d let me get a couple of points, maybe win a set. He knew we had to give the audience some entertainment. In private, though, he’d always just thrash me.

In the 70s I was vilified for the Confessions films but in an interview, Leonard stuck up for them. He called me and the other actors giants and said that it was brave to introduce this new concept of nudity into comedies. It meant a lot that he said we weren’t crap.

In 1973, Rossiter stars in The Banana Box, a new play by Eric Chappell, about a seedy boarding house owner and his unlucky lodgers. The play is picked up by ITV and becomes Rising Damp. Ratings regularly hit 18m.

Don Warrington: My first day with him was like meeting your hero. When the play turned into a series, he asked for me and Frances to be in it with him.

He was tough but helpful. He gave me direct notes: if you do it that way, it’s not funny. If you do it this way, it’s right. It was good to have somebody there with his professional standing and his obvious knowledge of comedy, who also had the language to help a young actor. He didn’t like when people came in and thought doing a situation comedy was easy, that they could just stroll through it. He made them aware that this was serious.

He was also a very private man. You didn’t get to know him really, which was a shame. It would have been nice to know something of how he got where he got to.

Once, he asked if I’d like to play squash, as I felt I was rather good. I thought: this poor old man, I’ll give him a good hiding. And the opposite happened. He had a fantastic brain and knew how to manipulate the ball so that his opponent would have to work very, very hard. It was a good lesson. I looked on him fondly as a wise man on the way who taught me things for which I was grateful.

Camilla Waterman: I was relatively young when he died, so I know him as much through some of those performances. When I was growing up, I could watch Rising Damp and Reggie Perrin and it was a nice way to see him and feel a connection with him. Rising Damp especially: it’s not just him, it’s four incredibly strong performances. I think that’s why it stands up so well.

Don Warrington: He was constantly surprising me. He would do the opposite of what was obvious. In rehearsal you would see him working and working and working. Like Peter Sellers: he made it look easy because of all the work he’d done before.

Len knew how to ride a laugh, but he was more concerned with the integrity of the piece and keeping it organic. There can be a tendency sometimes to indulge the audience in their laughter, but he knew when it was time to stop.

He knew how to control an audience, so you didn’t dissipate what you were trying to do. In one episode, Rigsby is waving some “love wood”, which the audience found hysterical, but he would only let it go on for so long.

Dick Clement: His energy worked very well opposite Richard Beckinsale [with whom Clement worked on Porridge]. He was so laid back and never on edge. But for most of us, the energy actually bounced back at you. You wanted to keep up with it. You didn’t wanna slow him down. The only other person I can think of with that velocity is Rik Mayall.

Steven Berkoff: Few actors remind me of him, but James McAvoy does a little. He too has that sort of unsheathed electric cable inside him, which gives rise to perverse and idiosyncratic readings and interpretations. Lee Evans, too: astonishing physicality and mimicry.

Rossiter takes a bigger role in a 1975 Kubrick film: Barry Lyndon, starring Ryan O’Neal. He plays the pompous Captain Quin, who loses in a duel against Barry for the hand of Nora Brady (Gay Hamilton).

Jonathan Lynn: Once Kubrick met him, he never made a film without him.

Gay Hamilton: Leonard was always making us laugh. I do remember the interminable dancing scene. We did retake after retake all day, until we were ready to drop. Leonard was not at all pleased about how long it all took and made some pretty wry faces.

Steven Berkoff: We were both in Barry Lyndon but never shared a scene. Kubrick admired him inordinately, because Len never made a fuss: he just got up there and did it. Never asked a question – not interested. A trooper.

Gay Hamilton: I also recall him getting quite shirty with me, because in a scene between the two of us, while Leonard was on camera, Ryan O’Neal was clowning around in the background, pulling faces and making me laugh. In general however, we got on very well and he was always very funny.

In 1975, Rossiter shoots a standalone TV film called Machinegunner, about a West Country debt collector.

Gabrielle Rose: I played a barmaid and I was pretty uptight because it was the first film I’d ever been in. We all went to the pub at lunch, and then we did the scene afterwards, and I was much better. They plied me with a couple of drinks and I was much looser. I’m sure that’s why we went, actually.

Leonard was an extraordinary human being. He was really generous and at the same time, very strenuous in his need for things to be perfect. I was super-young and inexperienced and he had a lot of patience with me, which I thought was amazing. He was a really educated man, and also open-minded. A man of the world.

Later that year, Frances de la Tour leaves Rising Damp for half of the second series, later rejoining for the remaining two. A new character, Brenda, joins the show in her absence.

Gabrielle Rose: They were looking for a young woman and maybe Leonard said: “Oh, I just worked with a young woman.” I was pretty scared all the way through, but I also felt really in safe hands when I was in front of the cameras with him. He would rescue the situation if it fell apart. So there was a relaxation because it wasn’t about my character, it was about his character. And Brenda was a good juxtaposition: sure of herself and kind of sexy and pretty offhand.

Once I flubbed a line, and afterwards he said: “The only way you can get a retake is to swear.” But he was the only one who had the guts to do it – and the audience loved when he did. He loved performance, just bloomed when he got there. That kinetic energy went all through so his whole body would be kind of shaking. The crowd just loved him to pieces.

He had this tremendous energy that was addictive. You could catch it. He had an ability to pull everybody in and get everybody kind of worked up and get everybody moving fast, like a dynamo. He found the work delicious.

We would go out for dinner afterwards. Everybody would just sit around and have a drink and take it apart and put it back together again. I was pretty quiet but Leonard was so magnetic; just mesmerising. That’s charisma, right? He wasn’t a classically handsome man, but he had real star quality. It was hard not to stare at him all the time. It must be nice to have people not able to turn away from you.

In 1976 Rossiter begins work on David Nobbs’ The Fall and Rise of Reginald Perrin, about a disillusioned sales executive in suburbia who fakes his own death.

Camilla Waterman: As a young man stuck in insurance there must have been elements of the dissatisfaction he could relate to. Frustration with a mundane nine-to-five life.

Tim Preece: I played his son-in-law. He was fun to work with, but exacting – rehearsals would be careful and carefully paced, but when the audience was in each week the tempo lifted, and the rest of the cast had to work hard to keep up.

His work was meticulous. He once stopped a pre-performance run-through because an ashtray or something, a prop, was wrong, and everyone had stop to until it had been put exactly right, and of course he was right: the prop affected the timing.

Camilla Waterman: My mum’s mother – so Dad’s mother in law – once very proudly went along to the filming of an episode and Dad got her to stand up and told the audience: “This is my very own hippopotamus!” They all clapped and she was thrilled!

Tim Preece: I don’t think it holds up now. It’s of its time in that it treats the women as a means of making a joke.

Len was not starry, he was a modest man. Down to earth. Feet on the ground. But he was competitive, as I knew from getting to know him through cricket. I think I once bowled him out. I once allowed myself to play him at squash which was something of a nightmare. But we were very much a family on Perrin. We all got on. We used to meet up for about three years after but then people dropped off the edge.

Camilla Waterman: John Barron [who played Perrin’s boss, CJ, on the show] introduced Dad to vintage wine. He became very enthusiastic. He and my mum would have dinner parties with friends, usually actors, writers, directors. He was very gregarious and sociable.

Jonathan Lynn: He took such perfect care of his wine that he always felt he could always resell it. He never did.

Joe McGrath [his later director on the Rising Damp movie]: He would sometimes say: don’t go into that pub, they don’t have any good wine. He loved good food, too. One thing he did not like was someone asking for his autograph in a restaurant. He’d tell them to piss off – in so many words.

Camilla Waterman: The fame and recognition was never something I think he particularly enjoyed.

As the sitcoms wind down, Rossiter returns to more experimental work, including a one-man stage show about the painter and diarist Benjamin Robert Haydon.

Neil Pearson: I saw it when I was at drama school and thought: “God, I’d quite like to do something like that.” It was extraordinary.

Alan Strachan: I jumped at the offer to work with him directing Haydon. He was on top form, mastering a long text and handling both the pathos and the comedy. Rehearsals were thoroughly enjoyable.

This, however, was not the case on a revival of David Turner’s Semi-Detached the next year. He still resented being spurned for the Broadway and West End productions. He insisted on directing, although Bernard Miles of the Mermaid theatre insisted he have a co-director (me). Rarely a good idea.

Clearly he wanted a replica of the [original 1963] Coventry production, hardly possible with a mostly different cast and co-director. He could be spectacularly rude or dismissive to the cast. I tried, after rehearsals, to temper his behaviour and he would behave for a few days before resuming his hectoring attitude.

He took little notice of my attempts to tone down his frenetic speed, which could make him too often hard to understand. The notices were poor, especially mentioning his manic pace. He was much more controlled during the Greenwich run and on the subsequent tour.

In 1981, Rossiter stars in a landmark Play for Today, The Factory, opposite a young Ray Winstone, and makes a 40-minute film in which he plays legendary farting musician Joseph Pujol.

Camilla Waterman: I could imagine a lot of actors thinking I’m not going to do that because it’s actually quite weird. I don’t think he was sort of afraid to do things that were a little offbeat and unusual.

In 1978, he’s the top-billed guest in the Christmas episode of Morecambe and Wise, in which the three men impersonate the Andrews sisters.

Camilla Waterman: I absolutely love that sketch. It’s just so silly, and in drag he also looks exactly like his mother.

Rossiter shoots another sitcom, The Losers, set in the world of boxing and the screen debut of Alfred Molina. The show is directed by Joe McGrath, who Rossiter then ropes in to direct the big-screen version of Rising Damp. The film repurposes much of Chappell’s original scripts, but without Richard Beckinsale, who had died of a heart attack, aged 31, in 1979. Beckinsale had not appeared in the final season of the show, due to theatrical commitments.

Joe McGrath: Richard’s death raised the stakes a lot and Len was aware of that. He said to me: we lost the best actor. I didn’t want him to think he was making another version of Rising Damp, because TV and film are so different. But he was a very bright man and had no problem understanding that.

He didn’t have any side. But most actors are very insecure and I think he was too. You’d do a take and he’d come up after and have a quiet word afterwards because he was worried about it. Peter Sellers was the same. But we became good friends and went on holiday together with our wives to Spain. He just loved swimming.

Camilla Waterman: On holiday he taught me and said if you can swim a width of the pool, I’ll give you a pound. Which would then have been quite a major statement. I was delighted and he was thrilled.

He was very nervous of flying. My mother’s theory was that it was because somebody else was in control. So we had to get ferries and trains and things and it became ridiculous. And he did then force himself to go on planes. But I don’t think he ever enjoyed it.

When I was about 10, I went on a school trip to Hastings. There had recently been a few coach crashes on the motorway, and so Dad insisted on driving me there himself, waiting around all day, then driving me home. Looking back now I completely sympathise. Of course at the time I just thought, oh my God, this is embarrassing.

But he very much valued education and wanted me to perhaps have those opportunities he wouldn’t have been able to from a financial point of view. When I sat exams for secondary schools and got into all of them, that was something that he was very proud of.

From 1978 to 1983, Rossiter stars with Joan Collins in a series of adverts for Cinzano, directed by Alan Parker and then Hugh Hudson.

Steven Berkoff: He functioned by pushing himself to the limit, even just doing a commercial. Usually actors take it down a peg; he’d go all out, sometimes even more so.

Camilla Waterman: I like the kind of the relationship between him and Joan Collins and the slightly bizarre world they seem to exist in. My mum would say that when they’d go out, the barman would always see my dad and laugh and say, “Mr Rossiter, it’ll be a Martini, will it?” They’d always say Martini. So much so that my dad apparently talked to the Cinzano people at one point about whether the adverts were really working.

When ITV went on strike, apparently they had more complaints from viewers that they couldn’t see the Cinzano ads than they did about missing any programmes. They were really popular: working out how on earth he was going to chuck the drink over her this time.

In 1982, Rossiter shoots NHS satire Britannia Hospital, directed by Lindsay Anderson.

Robin Askwith: We shot in a functioning mental asylum in north London. I remember queuing up for lunch one day and the woman doshing out food said to Leonard: “Uh, no, the patients are fed at two.” He went ballistic, and that just made things worse.

He was always very encouraging and we spent most of our time together. Joan Plowright got a bit miffed with us as we slightly excluded her from conversations. She said: “I don’t feel like I’m one of the gang.”

At the start of 1984, Rossiter signs on to play a role which could have been written for him (and some believe originally was): Inspector Truscott in a major revival of Joe Orton’s Loot, set in a dubious funeral parlour.

Camilla Waterman: He was starting a new phase of his career. People were starting to be ready to see him as not just Rigsby or Reggie. He was starting to do work that might have been memorable in other ways.

Jonathan Lynn: I first worked with Len in 1983 on a corporate advertising film for Barclays called Mick’s People and found him excessively difficult. He could be phenomenally awkward. He was intolerant, had an attitude and didn’t admire any of the the rest of the cast. On the last day, when he wasn’t there, they ordered champagne.

So I was amazed when a short time later I got a message from Ray Cooney saying he was producing Loot and Len wanted me to direct him. At first I thought they must mean Jonathan Miller, and then I thought well: how bad can it be for just a month? But it turned out to be one of the best experiences I’ve ever had, and Len and I grew to be tremendously good friends.

I asked him if he wanted four or five weeks rehearsal? He said: “Christ, two, we can’t fuck around with all this time-wasting.” I consulted him on all the casting because I didn’t want him to turn around and say, “Why did you cast that amateur?” That was the biggest insult he could produce.

Neil Pearson: He’d seen me on a Play for Today and suggested me. I think he was looking for people who could look after themselves. On the first day of rehearsals, we did a totally blind run-through, just to get the feel for it. Leonard was hysterical.

Jonathan Lynn: He was word perfect, almost ready to go on. The others couldn’t deal with that.

Neil Pearson: At the end when we stopped laughing, Paul [McGann] and I looked at each other and said, Jesus, that’s where he starts. We’re gonna have to run very fast than to keep up.

Neil Pearson: He was extraordinarily precise. His almost sort of epileptic, constantly moving, constantly sort of feverishly physical, was very cleverly planned.

Paul McGann: Working with Leonard was the sternest acting lesson I was ever given. Being a young actor and a bit half-arsed, two things he appeared to loathe equally, I got the silent treatment from him during rehearsals and was expected to speak only when my character did. I felt both intimidated and awed.

Jonathan Lynn: Once, we were rehearsing the opening scene, in which Len isn’t in. He said: “They’re not doing what you told them to do yesterday.” I said: “It takes many actors a little time to assimilate a note.” He said, “Well, it’s no fucking good.” I said: “Would you like to direct this?” He said: “No, no, I directed once and it was a disaster. I couldn’t understand why they didn’t just fucking do it.” A few days later they were having trouble with a scene and Len intervened just to say: “Look, no method shit here.”

Neil Pearson: He got frustrated we couldn’t see the funniest way to do it as quickly as he could. I got the feeling at times he felt we were holding him back and exasperated when we didn’t find the best way by ourselves. I think everyone who worked with him would have come out of the experience possibly a little shaken but certainly knowing a lot more about how to get laugh.

Paul McGann: To this day I’ve not seen another actor combine comedic deftness and menace the way Leonard could.

Jonathan Lynn: He was utterly brilliant. He was completely in control of his instrument: himself. He could do everything instantly, with tremendous facility. If I gave him a note he thought was right, he was mainly slightly irritated he hadn’t thought of it himself.

He had the best natural timing of any actor I’ve ever worked with, and was the funniest man I’ve ever worked with. He was also highly attuned to the audience in a way I’ve never encountered before. Most star actors stay in their dressing room until the last minute. Len listened to the audience coming in, through the curtain and over the tannoy.

Camilla Waterman: He would have thought: these people have worked hard, booked their ticket, maybe their babysitter, paid for their taxi. Coming from a background that wasn’t privileged he was very aware of the value of money.

Even with the telly he thought: they’ve sat down after a hard day’s work, they’ve chosen to turn on our show, so we’ve got to give them 100%. He would’ve felt that responsibility particularly as he got more successful and aware he was one of the reasons people were coming to watch.

Jonathan Lynn: He’d listen in every night and then, if the opening few minutes were a little bit too rushed or a little bit slow, if the timing wasn’t precisely what it should be, as soon as he came on, he corrected that. Within a minute or two of Len coming on the stage, everything was going at precisely the right pace.

Neil Pearson: He was a cool and clinical and very unBritish farceur. And when farce works best, it works like a Swiss watch. He certainly saw the production as a nut to crack, just as an athlete is looking to under 10 seconds for 100m. His approach was scientific and it was like an elite sportsman.

Dick Clement: He was fantastic in Loot. Like watching a tightrope walker, you hold your breath while they’re doing it.

Neil Pearson: With drama there are a million ways of doing it. Rossiter was a big believer in the one way of doing a comedy being the funniest way. Once you found that way, your job is not to try things out but to do it the same. Not to let it grow stale, but to keep it alive and keep it at the pitch at which you found audiences laugh the longest. On the rare occasions a line slipped or a prop didn’t behave, it would make him very angry in the way that a sportsman gets angry when they miss a shot.

He liked to have a cool-down after the show, and we’d all go to the pub for a couple of drinks.

Paul McGann: I remember having just one conversation with him, one night towards the end of the run when we found ourselves the last two people in the pub after a show. I’d been doing a ludicrous London accent for the play and remember his surprise when we spoke that I was actually Scouse.

After some awkward small talk we landed on the safe subject of football. He, naturally, had played a bit and mentioned a 1950s Liverpool business houses league and was amazed when I knew its name. I told him my Dad had played in it too. A minute later he asked, “Did your Dad have an older brother and they’d play centre-half and centre forward?”

Exactly right, I said.

He’d only played against him.

Neil Pearson: We didn’t talk that much. There was the age gap, and politically we were different; he was quite Conservative.

Steven Berkoff: He was just a straightforward man of the people with attitudes to wages that were pretty current at that time. He was certainly never racist or prejudiced.

Jonathan Lynn: He was right-wing but a very active trade unionist. He would have had zero tolerance for all of the recent Tory leaders.

Neil Pearson: But if you asked him about comedy down the pub, you’d get an hour-and-a-half. I once asked him what he found funny, and he did said: Jack Benny. Benny did the absolute opposite to Rossiter to get a laugh. For Leonard, watching someone on stage who could do apparently absolutely nothing except pause, for hours on end, and then raise an eyebrow and then bring the house was something that for him was witchcraft. Like close up magic. He had a hankering for the thing that he couldn’t do.

Camilla Waterman: At home, we’d watch films together: comedies and old black and white films like The Third Man and Strangers on a Train. He adored the Marx brothers.

When I was about six or seven we went to a pantomime at the Palladium. They used to get kids up on stage, and I went up - they didn’t know I was his daughter - and I must have said something and the audience laughed. After that he would apparently go around saying, “Well, she got a laugh at the Palladium. That’s more than I’ve ever done.”

The play has a hiatus between May and September, when it moves from the Ambassador’s theatre to the Lyric. During this time, Rossiter shoots a new sitcom, Tripper’s Day, set in a supermarket.

David John: I was 23 when I got an audition and was really excited to meet this comic genius. But Tripper’s Day turned out not to be what we all hoped it would. The atmosphere was quite stressed.

I remember one incident in rehearsals when Leonard was working out his moves and the director said: you can’t go there, because one of the cameras will be there. And Leonard said: “No, no, no. Stop, That’s not the way it works. We work out how to make the scene funny, and then you decide where to put the cameras.”

I never found him difficult. He was really friendly to the three or four of us young lads on the show. We played cricket in the car park during all the breaks. One day he asked if I’d seen Loot – I’d seen the opening night because I was friends with Paul McGann. Leonard said I would be great in the part Paul was going to leave the show once the moved to the Lyric. So Len got me the job.

It meant so much to me, his putting his arm round my shoulder and saying I was good enough. He would always give you little notes through the run about how you could improve things, but he was very generous and give you your moments and laughs. Never upstage you or cut over a line to take the laugh himself. He was all about the work and the camaraderie and the friendship and I absolutely loved him.

He was in his element on that play. I was in awe of him every night and the audience was in the palm of his hand. I’ve never known anything like it since: someone with such control of the house. You’d feel the room crackling with an incredible electricity.

Camilla Waterman: Loot was a really, really big success. And he loved doing it. It was a very happy company, and he loved Jonathan Lynn. They got on so well.

Jonathan Lynn: He never changed as a person. Most other leading actors would’ve asked for a limo to take them home after the show. He took the bus, top deck. I said: “What if people recognise you?” He said: “If they’re polite, I talk to them. If they’re rude, I tell ‘em to fuck off.” I think it would have been about 50/50.

He’s the only actor I’ve ever seen outside the theatre at 11pm with a ruler measuring the size of his billing on the poster to make sure it was according to the contract.

It was all running like clockwork, but I would still see him for dinner parties quite a lot. Once he was your friend, he was completely open-hearted and generous and warm and not remotely difficult. And he was always kind and never patronising with our 11-year-old son, Teddy. Whenever he came to our house he always found time to have a proper chat with him, usually about sport. He was also very affectionate with our bearded collie, Humphrey.

David John: He was so happy, and it was one of the happiest times I’ve ever had, until it became the complete opposite, the worst time.

One night after the show, he said he felt a bit chesty and would just have one pint and get himself checked over the next day. The understudy said: “Oh, I better look at the script.” And Len said: “No, no, don’t worry about that. I’ve never been off in my whole life. I don’t intend to start now.”

The next night he did his first scene and as he came off and I was waiting in the wings we did our usual evening greeting. I asked how the doctor went. He gave a thumbs up and said: “No problem. He said I’m as fit as a fiddle.” I went on and did my scene, then went to my dressing room.

Neil Pearson: I was on stage with Gemma Craven. We always knew when Len was about to come on as the audience would see him behind a frosted glass window and there would be a gasp. But that night there was no gasp. We carried on for a while. I left as my character was meant to go and start a car and Gemma filled for time.

Then I learnt that his dressing room door was locked. So I came back on and said something like: “I’m sorry, ladies and gentlemen, we have a slight problem. We’re going to bring the curtain down but we’ll be back with you as soon as possible.”

David John: I heard Neil and Gemma improvising and the stage management calling him to the stage immediately. That was unprecedented for a professional like Len. So I just ran to his room and we got his door open and there he was, sat in his chair.

I don’t think I was prepared to accept he was dead. I gave him chest massages for a long time, but Gemma felt his wrist and just said: “He’s dead.” A couple of doctors from the audience had come in with Neil, and Frances de la Tour was there too, as she’d been in to see the show that night.

The paramedics came and put breathing apparatus on him and took him out. The stage manager was going: “Come on, come on everyone, the show must go on.” The understudy was utterly terrified. He had to get into the costume and carry on to this massive packed house, standing room only.

Jonathan Lynn: That’s what you do – you carry on. You really don’t want to be the man who goes on stage and says, “I’m awfully sorry, but Mr Rossiter has died, so go home.”

David John: I’ll never forget the torture of that night, having to carry on doing that play about disrespect to the dead. Then we were stuck there for hours, because the tabloid press surrounded the theatre.

Jonathan Lynn: I’d been at the cinema and when I got home, there was a phone message from the company manager. I couldn’t believe my ears. So I jumped in the car and went in. Finally the press seemed to get tired and went away.

Robin Askwith: I was working in the next door theatre, in a production of Run for your Wife. I was very upset. Though when you’re that young and and somebody’s in their 50s, you think: “Oh, well there you go.”

Jonathan Lynn: I was in a state of complete shock. I was profoundly upset. I was overwhelmed. Some Guardian writer said you can tell how great an actor is by who can fill the gap they leave when they die. There was really nobody who could, or ever has. He was unique.

Steven Berkoff: I was absolutely shocked. It was unfathomable to me. He was unequaled in so many ways. I thought of him as a real ally and a chum.

Paul McGann: I heard about Leonard’s death as as were preparing to leave to go travelling with friends. I remember feeling shock but strangely little surprise, at least on hearing it was his heart. My dad had died a few weeks before — his heart too — and something in Leonard’s physical presence had reminded me of Dad’s.

Camilla Waterman: I think a lot of people believe that it was a heart attack, which it actually wasn’t. It was a heart condition that you are born with - and often, ironically, it affects people who are very athletic.

Neil Pearson: It was a heart cramp. He was so fit. At the time of his death he was seeded the fourth best amateur squash player in the country. Not for his age, but overall.

Camilla Waterman: The condition is something to do with the muscles of the heart. So it was one of those things that was going to happen at some point. It could have been in his 20s or his 80s.

The play continues with the understudy playing Truscott, before the decision is made to formally recast the lead.

David John: The management still thought there was some kind of future for the show. So we were then rehearsing all day with his replacement, Dinsdale Landen, and then performing at night. It was so grim. They wouldn’t give us a day off, just vitamin B12 injections.

Jonathan Lynn: Obviously it was a big mistake not to have closed the show.

David John: Dinsdale was a different sort of actor and it didn’t work. Of course it didn’t: someone coming halfway through to replace someone like Leonard just felt so wrong.

Neil Pearson: Because of the subject of the play, the theatre was already draped out as if for a funeral. I remember letters afterwards from people saying that was very tasteless. It was a very strange time. A black comedy just went black.

David John: We were totally traumatised and exhausted. I’d never experienced death, and I’d found him. It was all really horrendous and that kind of early experience changes your aspect on a lot of things. It’s one of the reasons I’m so active in Equity now. I think some of the old theatre practices must be resisted.

It really hit me when they refused to let us attend the funeral because it was a matinee day. Only about 200 people were going to come because everyone was cancelling their tickets. The actors refused to do it and the management said we’d be in breach of contract. They kept saying: “Leonard would want you to carry on,” and we said, “Well, he’s not here, and we want to go to his funeral.” Which we did.

Jonathan Lynn: I was asked to give the eulogy. It was hard because there were 1,000 people in St Paul’s Church in Covent Garden, and I couldn’t stand up and give one of those speeches about how delightful and easy he was to work with. So I talked about how he was a perfectionist, and I wondered if God knew what he was in for. The pearly gates had better open on cue. The heavenly chorus better be in tune.

Camilla Waterman: If you could have asked him how he’d like to die: in a theatre with a very happy company, in a very successful production, working for a director who he got on extremely well with – I think he probably would’ve taken that. My mother would always say: “Thank goodness he wasn’t ill for a very long time, because he would’ve been a terrible patient.” So I think it was kind of a fitting exit.

I wish I’d had the chance to have a relationship with him as an adult. I think he’d have been quite a formidable father-in-law but I know he’d have been an absolutely doting granddad and would have adored my daughter. But although it was awful for us as a family, it also must have been so awful for the company and the people in the audience.

Half a dozen film and TV projects are released following Rossiter’s death, including the remaining episodes of Tripper’s Day, a version of Alice in Wonderland, a BBC Shakespeare production of King John, Water (a film opposite Michael Caine) and standalone TV drama Moon Over Soho, in which he plays a German magazine writer.

Dick Clement: I wrote Water and loved his role as a civil servant who was the pain in the arse. It was something Len could do in his sleep. But he still had boundless energy and incredible professionalism and attack: menace combined with that brilliant comic timing.

Peter Ansorge: On Moon Over Soho, we had two weeks of rehearsal and then shot over two days. Leonard went straight into talking about what he did and didn’t like about the script. No waffling, no small talk. He’d lose interest immediately if you started talking about how much you liked Rising Damp.

He had this incredible intellectual energy and would talk about the process without it ever being boring or Stanislavsian. There was no nightmarish self-indulgence. In that sense he was similar to Maggie Smith: they both just had an acute sense of how to deliver a line for maximum cut-through.

It was Lesley Manville’s first major part and he was really good with her. He wasn’t ever overwhelming and didn’t want to destroy everybody else’s performance, as Olivier sometimes could.

It wasn’t broadcast until August 1985. I remember Nancy Banks Smith said in her review that it was a warning to actors to be careful what you choose, as anything could turn out to be your last role. But it was watched by six million - a big audience for a single play – and it’s now on YouTube. My son says it has a little bit of a fan club.

Jonathan Lynn: There’s so much he could have gone on to do. I had written a part for him in my first film, Clue, which Tim Curry ended up playing.

Joe McGrath: He loved European cinema. He could have worked with those directors more. Done another film with Schlesinger.

Tim Preece: I wish we’d had the chance to see Len’s King Lear. Had he not died as as early as he did, he would have become one of our iconic later age actors. It would have been great to see him tackle Ibsen and Chekov with those gritty hands. The National Theatre should have taken him on, but I doubt he got on with Olivier and that lot which ran things then. Len wouldn’t have played that game.

Camila Waterman: It’s sad to think of what he might have done. I always think he’d have been great doing a Dickens costume drama, as Mr Jaggers or someone like that. But he had a great life in the sense that he came late to acting and made a huge success of it.

People have such clear memories of Rigsby and Reggie Perrin and they’re both quite strong characters. Of course he wasn’t remotely like either of them, but whenever people find out I’m his daughter and they’re really lovely and say: “Oh God, I remember those shows, they were so funny.” So I’m very, very proud that he is still remembered with great fondness and admiration.

• This article was amended on 5 October 2024. In an earlier version, a picture caption misidentified Leslie Schofield as Tim Preece.