There have been few genuine clowns in theatre and television as good as Denise Coffey, who has died aged 85. She was a key TV presence in British comedy over its most redefining postwar period, and to see her on stage, always puckish and delightful, was to invest in two or three hours of an invaluable spiritual tonic.

She was a crucial member of the ebullient Young Vic company formed in 1970 under the aegis of the National Theatre at the Old Vic to deliver classics and new plays with regard to a younger audience. She had already, in the 1960s, played a series of classical and low-life roles at Bernard Miles’s Mermaid theatre in Puddle Dock.

She emerged at the Young Vic, under Frank Dunlop’s direction, trailing several film credits and a high profile in surreal television comedy – notably in ITV’s Do Not Adjust Your Set (1967-69) – influenced by the radio comedy of the Goons and prefiguring Monty Python. She and David Jason formed the “legit showbiz” element in a company of university wits – Michael Palin, Terry Jones, Eric Idle, the producer Humphrey Barclay – with musical incursions from Vivian Stanshall’s delirious Bonzo Dog Doo-Dah Band.

There followed two popular series on ITV: Girls About Town (1970-71) in which she and the singer Julie Stevens were living it large in Acacia Avenue; and Hold the Front Page (1974), in which Coffey led a bunch of crazy newsroom assistants chasing down a “Mr Big” involved in a Great Rug Scandal. End of Part One (1979) was a satirical soap in which Mr and Mrs Straightman (Tony Aitken and Coffey as Norman and Vera) were disrupted in their domestic dullness by a panoply of famous people on television; Coffey herself turned up as Robin Day in those trademark cruel glasses.

She was a total one-off: under five feet tall, elfin-looking, punchy and eccentric. In her private life, she was determinedly single, vegetarian and finally remote, especially after she discovered the joys of the West Country – she moved from London to Salcombe in Devon – and living by the sea.

She was a regular in a couple of Stanley Baxter’s TV comedy series in 1968 and 1971 and went wildly over the top as the grotesque manager of Alexei Sayle’s hopeless nightclub comedian, Bobby Chariot, in Sayle’s Merry-Go-Round in 1998.

Denise was born in Aldershot, Hampshire, the only child of Dorothy (nee Malcolm), and her husband, Denis Coffey, a proud Irishman from Cork and squadron leader in the RAF. They moved north to Dorothy’s native Scotland, living near Inverkeithing in Fife and later in Milesmark outside Dunfermline, where Denise was educated at Dunfermline high school and trained at the Glasgow College of Drama and the Royal Scottish Academy of Music.

She made a professional acting debut at the Opera House, Dunfermline, in 1954, “as various apparitions” in Macbeth. By 1962, she was playing the star turn, the word-mangling Mrs Malaprop, in Sheridan’s The Rivals at the Gateway in Edinburgh and then, in 1963, the insalubrious Mrs Coaxer in a revival of John Gay’s The Beggar’s Opera for the Royal Shakespeare Company at the Aldwych in London (alongside Dorothy Tutin, Patience Collier and Elizabeth Spriggs); she was pressing her claims to join the top table.

A West End highlight was playing the maid, Edith, in High Spirits, a Broadway musical version of Noël Coward’s Blithe Spirit, directed by Coward himself, at the Savoy theatre in 1964, in a cast including Denis Quilley, Marti Stevens and Cecily Courtneidge.

She had made a television debut in 1959 in a BBC adaptation of Walter Scott’s Redgauntlet and consolidated her theatre reputation at the Mermaid in various classics and new plays, notably as 19-year-old Fanny O’Dowda in George Bernard Shaw’s Fanny’s First Play – as a prosecuted suffragist turned feminist playwright; and as the non-speaking but occasionally flatulent Cicely Bumtrinket – a favourite role, not even identified in most cast lists – in Thomas Dekker’s Elizabethan city comedy The Shoemaker’s Holiday.

She also featured in several important 60s films: as Peter Sellers’s eccentric daughter Sidonia Fitzjohn (alongside Prunella Scales as her sister) in John Guillermin’s Waltz of the Toreadors (1962); as Lynn Redgrave’s mousy little friend, Peg, in Georgy Girl (1966); and as Soberness in John Schlesinger’s Far from the Madding Crowd (1967) starring Julie Christie and Alan Bates.

On location in Dorset for the last of these, she visited nearby Devon, where she would return to live permanently. But not before her Young Vic stint – as both actor and associate director – in the 70s, where she was a standout company member alongside Jim Dale, Jane Lapotaire, Andrew Robertson and Nicky Henson.

Her roles, all invested with incomparable zest and cheek, included Beatrice in Much Ado, a rare double of Mistress Overdone and Mariana in Measure for Measure and Doll Common in Ben Jonson’s The Alchemist. She toured Europe and north America with the company, appearing with them at the Edinburgh festivals of 1967, 1971 and 1972, notably as a harassed Scottish housewife in a Comedy of Errors relocated from Ephesus to Edinburgh.

When her mentor Dunlop was appointed director of the festival in 1985, she provided a brilliant Scottish version of Molière’s Le Bourgeois Gentilhomme – A Wee Touch of Class – starring Rikki Fulton as “Archibald” (real name, Charles) Jenner, the 19th-century founder of the famous store, Jenners, on Princes Street; Coffey was Netty, a scrofulous clog-dancing servant from Fife.

She appeared in a fine, early Film on Four, Michael Radford’s Another Time, Another Place (1983). Her work on radio included guest appearances on I’m Sorry I Haven’t a Clue and Just a Minute, and two series by Sue Limb: The Wordsmiths of Gorsemere (1985-87), a very funny send-up of the Lakeland poets, Coffey herself as Dorothy Wordsmith, Tim Curry as Lord Biro and Simon Callow as Samuel Tailor Cholericke; and Alison and Maud (2002-04), teaming with Miriam Margolyes as a pair of bizarrely eccentric landladies.

A 1980 film written by Stanshall, Sir Henry at Rawlinson End, in which she played a tapeworm-obsessed woman called Mrs E, won cult status when issued on DVD in 2006. “It’s impossible to do justice,” said the critic Nigel Andrews, “to the film’s arrant and quite unique lunacy.” In the 80s, in Canada, she directed plays for John Neville at his Neptune theatre in Halifax, Nova Scotia, and for Christopher Newton at the Shaw festival in Niagara-on-the-Lake, Ontario.

Her output was increasingly sporadic as she happily hunkered down in Salcombe, “exploring my artistic bent”, fishing in a small boat with a tiny outboard motor, gardening and making rare excursions to London, always travelling by taxi.

She is survived by a cousin, Linda.

• Denise Dorothy Coffey, actor and writer, born 12 December 1936; died 24 March 2022