So far, Bill Nighy has been offered a seat on the tube on 10 separate occasions. “Not that I’m counting. But obviously I am.” He snorts. “The worst thing is everyone in the carriage turns to look and see what you say.”

Always a polite decline. “Last week, I was carrying my gym bag and I felt like saying: ‘You know, I’ve just been doing quite vigorous things. And I can actually remain upright for quite long periods of time.’”

He snorts again: the signature Nighy sound, unmistakable as a chiffchaff. It’s the same with stairs, he sighs; he’s forever being steered towards the lift. “The first couple of times, I couldn’t understand it. ‘Are the stairs … unsafe? Oh! Stairs! Am I OK with the stairs? Yeah, stairs are OK. I’m not bad on the stairs, y’know.’”

Does Nighy look in urgent need of a sit-down? Or are people just really keen to offer? Here, after all, is one of the world’s few actual rock star actors. “He has a brand,” says his latest director, Oliver Hermanus. “A singular type of British cool.”

His hangdog sex-god languor remains immaculate, regardless of the squid (Pirates of the Caribbean) or ninny (Emma), naff has-been (Love, Actually) or withered civil servant (his new one, Living) he’s currently playing.

Spend any time in Pimlico and you’re all but guaranteed a sighting. Navy Dunhill suit, Cutler and Gross specs, suave and obliging for the selfies. His appeal was never predicated on plump youth. And, at 72, he’s still whippet-thin: vigorous things, plus a strict regime of restaurant-only dining and a bare fridge.

How did he cope in lockdown? Ah, he smiles. He rented an Airbnb in the Suffolk countryside near his family (ex Diana Quick, their daughter, Mary, her two children) and the woman who ran it asked if he’d like her to cook for him. “I said: ‘I would love you to cook for me … ’”

Small wonder he assumes people leap to their feet at the sight of him because he looks so decrepit. He recently had his cataracts done. “When you remove the bandages, then you see how old you are. I thought: ‘Oh! That’s why people behave so weirdly around me.’ Because I had been living behind, y’know, quite a serious film.”

Again, mostly his own neuroses. He’s long been allergic to his face. No looking at photos, or films, or interviews. “I gave it up because – as a practical thing – I have to go to work. I can’t have all that rolling around in my head. So I don’t keep track. But then occasionally I’ll catch a glimpse of myself. And you go: ‘Jesus, God almighty. Wow.’”

He keels gently in his chair. We’re in Soho and Nighy has water with ice and a fat wedge of lime. He hasn’t drunk alcohol since 17 May 1992 – that hard-living history fuels the louche vibes – and, perhaps to compensate, always seems to style up the mundane.

Shooting The Best Exotic Marigold Hotel in India in 2015, he took his own Yorkshire teabags and decanted Marmite into 30 tiny tubs to evade airport security. Behaviour that might seem mad from anyone else, but is transformed by Nighy into the height of aestheticism.

Shooting their new film in Mayfair last year, says co-star Aimee Lou Wood, he “somehow managed to source a table, chairs and beautiful Italian dinner for us seemingly out of nowhere. There was even a bit of table decoration. We sat eating arrabbiata in the middle of a busy London street while people walked past and waved.”

That film is Living, tailor-made for Nighy by its scriptwriter Kazuo Ishiguro, who asked if he might like to star in a remake of Kurosawa’s Ikiru. He would; it’s now his first proper shot at an Oscar. Nighy plays Mr Williams, a widower who oversees an office of paper-shufflers in post-war County Hall. A doctor tells him he has stomach cancer and six months to live. So he starts trying to do so, helped by a boozy playwright (Tom Burke) met on a botched suicide trip to the seaside, as well as Wood’s waitress and a sunny civil servant played by Alex Sharp.

What drew Ishiguro to Nighy, the former emails, was “his ability to arouse, seemingly at will, not only an audience’s emotions, but also its affection”. That makes Nighy “unique among his generation”; only Cary Grant and James Stewart are apt comparisons.

For Nighy, the character presented an irresistible challenge: how little can you get away with? Every movement is muted. He speaks in a desiccated whisper.

“I kept waiting for the soundman to come over and say: ‘Bill, I can’t hear a word.’” The Japanese and British share “a very elaborate code of conduct, performing their manners. And a kind of taboo on any public expression of deep emotion – or any emotion at all. I love doing that because I find it very moving. I find it also quite funny that there’s virtually nothing you can say or do. It’s sort of bonkers, obviously.”

Nighy was born in 1949, four years before the film is set. His first memory was getting a Coronation mug at a fete. “That black-and-white footage of kids playing in shorts,” says Nighy. “I was one of those kids.”

Living, he thinks, might be one of those movies that “refer to other movies as much as to real life. When you hear people talking about the 60s, I was there but I don’t recognise anything they say. Because only selected comment persists into the modern world. The way it actually was is entirely different.

“Conspicuously, today, there are other ways of behaving which are the opposite of restraint. But maybe not everybody in 1953 was as restrained as Mr Williams.”

Living is as far up Nighy’s alley as you can get without hitting the next street. He’s an old pro at bureaucrats awakened by girls in cafes. There’s also rain, cigarettes, Westminster, fabulous tailoring (Nighy has always avoided Shakespeare on account of the trousers) and lots about the transformative power of a trilby.

It’s the period in time to which he’s most drawn. Everyone hankers after an age about 60 or 70 years before, he once read. “Sixteenth century monks would complain that the modern world was going to pieces and that 70 years ago it was all fine. It’s how politicians can manipulate people by saying it used to be great. No, it didn’t. It was actually much worse. But there’s a sort of reflective nostalgia.”

Sometimes, that’s harnessed for the bad. At the moment, he thinks, “there’s a wave of reactionary thought, people trying to drag us backwards in time purely for self-advancement. It’s the easiest way to manipulate people: invent a past for which you can have bogus nostalgia and a future which is frightening and scary, largely because there are people of different ethnic origins. They’ve been doing it since I was a kid. The difference is, it’s digitised now.”

Anyway, back to the Blitz: Nighy knows it was horrendous but still hankers after it. “I think it’s to do with romance and sex. It unified people. They put aside any enthusiasm for division because they had bigger fish to fry.”

In fact, that fellow-feeling faded fast – though still a bit slower than it did after the early days of Covid. “How many times did you hear people say: ‘I hope we can hang on to some of this? Isn’t it great to hear the birdsong? To be in a clean environment? I hope people won’t just withdraw from one another again.’ And of course we’ve just pretty much gone back to normal.”

Nighy was raised in Caterham, halfway between Croydon and Crawley, by his mother, Catherine, a psychiatric nurse, and father, Alfred, a garage owner with natty sports jackets. The war was their big topic of conversation. “You were supposed to slip back into your life having seen dreadful, terrible things and been through an enormous amount of trauma.”

Alfred died of a heart attack when Bill was 25. The two men looked sufficiently similar that Catherine (who died in 2003) would go very quiet watching her son on screen. Some of Nighy’s stylings – social as well as sartorial – are emulation. “I did think about my dad making Living, because he was not unlike Mr Williams. He was a very nice person.”

Williams becomes galvanised by a modest project to construct a children’s playground on a bomb site: an 11th-hour attempt to be one of the kids getting stuck in on the swings, he says, not waiting for their mother on the sidelines.

Nighy was a fan of slides as a child, he says, “quite happy running and playing football. When I reached puberty it got complicated. I made a meal of it. I took it rather hard.” He overheard his mother saying he was shy. “Shy is a word I have difficulty with because I think there’s an enormous amount of vanity involved somewhere. But I aimed to please. I wanted to come top. I was an altar boy. I served mass five times a week.”

Nighy was all set for the seminary, but the call from God failed to materialise, not for lack of listening. Doubts began. “Certain people were gonna apparently burn in everlasting hellfire. People I knew. So you thought: ‘Maybe I should sort of say something?’ I remember asking questions and not getting any answers. And then I started worrying about my hair.”

At 15, he and a friend ran away to the Persian Gulf (“it looked good on the map”) and got as far as Marseilles. “We were very hungry and a bit scared because there were some very strange people on the docks.”

Back in Caterham, he was kicked out of grammar school and taken by his mother to the National Youth Employment Agency. “The bloke there had a big book of jobs and asked me what kind of thing I was interested in. I said: ‘Well, I wanna be an author.’ And my mother put her foot on mine under the desk and pressed down very, very hard, as if to say: ‘Don’t be so bloody stupid.’ And the bloke said: ‘Well, we don’t have any jobs for authors.’ And I said: ‘Well, I didn’t think you would. I just thought you’d best know.’”

Anyway, he did wangle Nighy work as a messenger boy on the Field magazine, going round posh London hotels changing their editions. “Sometimes they gave me the cab fare. It was all a bit, y’know, marvellous.”

He was less keen on the commute up to Victoria. “I remember thinking: if this is supposed to be my life, you have got to be kidding. This can’t happen. Too many people not saying anything crammed together. Awkward, embarrassing and uncomfortable.”

So, at 17, adventure No 2: to Paris, alone, “to write the great English short story. And I didn’t write a word.” He begged from tourists, was offered sex work but declined citing lack of experience.

Eventually he found his way to the Guildford School of Dance and Drama (“prance and murmur”), from there to rep in Liverpool, and touring the north with the likes of Jonathan Pryce and Julie Walters.

A decade of solid stage and radio work sustained him, just. In 1991, Sunday night serial The Men’s Room – shagging academics – upped his currency. He was in Arcadia and Skylight and Blue/Orange on stage; Lawless Heart, Still Crazy, Underworld, Shaun of the Dead at the cinema.

Love, Actually in 2003 saw another status upgrade. Skylight went to Broadway; so did another David Hare play, The Vertical Hour. On TV: award-winning turns in State of Play, The Lost Prince, Gideon’s Daughter and Page Eight.

Film credits became more prolific and prominent. Lots of big British hits: Pride, About Time, the Dad’s Army remake. Sometimes a bit of a blockbuster: Pirates, Harry Potter. Quiet dramas galore (Hope Gap, The Bookshop, Sometimes Always Never) but nothing with the kind of Oscars cut-through Living could manage.

Maybe Nighy’s shtick – hard to shift, because it’s genuine – can be a yoke? “I think his brand causes people to lose sight of his skill as an actor,” says Hermanus. He hopes Living “showcases his flexibility, the rigour of his process, and his capacity to deliver a heart-wrenching monologue as well as a twinkly one-liner”.

Every Sunday before the shoot, the director would head to Nighy’s place at 11am “and we would sit in his lounge and pore over the script. Bill would make us some tea. This is when we really bonded – talked about lives, our families and all the performances and films we love, and I would get to listen to the amazing array of music that he listens to – anything from bluegrass to hip-hop. I will remember my Sundays with Bill always.”

Nighy is not a method actor. Another reason lay-people love him is his habit of exploding his own profession. In one Bafta video, he recalls telling a drama student that, on stage, “I can absolutely guarantee you that I’m not feeling anything. I’m at work. I’m a bit busy. I’m a bit pushed. I have to achieve a total of about 15,000 things over about two-and-a-half hours. I can’t be feeling stuff. That I do in my own time.”

He’s catty about colleagues who fail to memorise their lines before rehearsals for fear it might stifle their creativity. Being off-book is a point of principle. “Wandering about saying the lines over and over and over and over so that you can eventually give an impression of spontaneity. That’s the job.”

Nighy talks about prep in the parlance of a footballer or a guitarist – both professions he much admires. Hours of keepy-uppy, endless perfecting the lick.

Ask co-stars about him and the jazz musician allusions flow freely. Burke says Nighy once “humbly suggested his entire oeuvre was based on ‘the double take’. He advocated double taking at: anyone entering in, any new information received, and he may have even pioneered double taking at one’s own private revelations, so a series of thoughts could fission out; exploding into the next one or interrupting the last; bringing something almost Chet Baker-like to actions as simple as entering, sitting down, and shifting to find a comfortable position. His liveness within such technical wizardry is what makes it so special.”

Burke, Wood, Sharp: they all rave about Nighy’s depth and discipline, openness and inclusivity, “gorgeous cheekiness, aliveness and playfulness” (Wood). The sense of letting you in on some magical private joke.

Sharp sends over more than 1,000 words of detailed praise. Sometimes he’d find a book in his trailer with a note saying: “Pertains to what we were talking about at dinner, a good read. Stay loose, baby – Bill”

“To say Bill is a good man is a fantastic understatement,” he writes. “He has helped me in my personal life in big ways.”

At another supper, Nighy told him about “a legendary actor, his senior, who he admired and loved” – and who is, I suspect, Michael Gambon. “He spoke of this man’s kindness and humanity, and how doing the simplest things, like fixing Bill’s tie when it was wonky, showed such kindness and respect for Bill, his junior, that it would fill Bill’s eyes with tears.

“This older actor’s work was of huge inspiration to him, but more than that, the essence of the man’s perspective, capacity for love, and natural inclination to create an equal playing ground with a younger actor, moved Bill beyond what he could articulate. He said he could never fully express this to him, but hoped he knew. Taking another bite of my food, I nodded, thinking: ‘I hope Bill knows that is exactly how I feel about him.’”

In Living, Williams is revived by the young. Nighy too? Not exactly, he says, then revises. “Thinking about it, I do find it refreshing to work with people of other generations. Older people can be kind of slightly besieged by life, or by the fact of their age.

“And I am unspeakably fortunate, beyond lucky. I don’t have anything I need to be younger for.”

In fact, he shudders, he’d hate it. Social media is “exactly what I don’t want. I don’t want to enumerate my friends. I’m working on less contact, not more.”

He tells me with horror that young people today must act as their own publicist. “Edit and curate and broadcast their own experience. That’s really tough. And if you are inexperienced and it gets combative … no wonder people become unhappy.”

Nighy’s people almost got him on Instagram, with the promise they’d do all the work. “But I pulled out. I just thought: I can’t. One of the things that I would’ve been required to do was to tell people that I’m in a film. I’m never gonna tell people I’m in a film. It’s just never gonna happen.”

At the London premiere of Living, he was asked by red carpet journalists what his favourite scene was. “And I couldn’t remember any of them. Normally, just to be sociable, I’d choose one. But I just didn’t have that kind of energy.

“There are certain PR questions to which there are only PR answers. It’s not lying, but it’s a very edited truth. And if you are in any way a moral creature, that’s probably why it’s sort of enervating. It’s a very particular kind of tiredness not because you’ve been doing anything dishonest, but it’s just not quite normal contact with other human beings.”

He hurriedly adds some qualifiers: it’s a champagne problem. And this isn’t abnormal. “This is nice and I’m not just smooth-talking.”

So I ask him what he would do if a doctor gave him six months. “I have no idea, honestly, Catherine. I’d want to spend time with my family. I might go somewhere distant and beautiful for a bit. But that would be worrying in case you started to, y’know, need some healthcare.”

Might he like to die by the sea, like Williams? He thinks he might. He goes to Aldeburgh quite a lot anyway. “It makes me philosophical, which is what you require sometimes.” The Shetlands could be good, he thinks. He talks briefly about how high a cliff he’d need. “I’d probably want to do it myself, rather than dwindle away in pain.”

Nighy once said he thought about death 12 times a day. He snorts, remembering the amazement. “That was quite a modest assessment. It’s probably more like 35.” Not all doomy, though: mostly whether or not shoes will outlive him.

He drains his water and the ice clinks. Noon with Nighy can feel like 3am with someone else. “And I don’t really believe it,” he says. That he’s going to die? “Yeah. I know it’s gonna happen, but I think maybe at the last minute somebody might make an exception.”

He leans back. “But then again, I sometimes think: I don’t think I can do a lot more of this. I’ve had quite a lot on.” He snorts again and I leave him, prepped for death, having the time of his life.

• Living is released on 4 November. Join the team behind Living, including Kazuo Ishiguro, Aimee Lou Wood and Oliver Hermanus, for a Guardian Live online event on Tuesday 1 November. Book tickets here.

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. For more information visit www.samaritans.org. In the US, the National Suicide Prevention Lifeline is at 800-273-8255 or chat for support. You can also text HOME to 741741 to connect with a crisis text line counselor. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at www.befrienders.org