Billie Whitelaw: Actress hailed as one of the finest of her generation, best known as Samuel Beckett's muse and inspiration

When she received her CBE from the Queen in 1991, she was so nervous she couldn't say a word

Whitelaw: 'I've never really felt like a proper actress,' she said (Rex)

The estate of Samuel Beckett is notorious for the vigilance it maintains over his theatrical legacy. A common complaint among contemporary interpreters has been that thanks to the estate's demands they end up with mere clones of the remarkable productions and performances that confirmed Billie Whitelaw as Beckett's muse and one of the finest actresses of her generation.

The pair met in 1963, when she was appearing in Play at the National Theatre, and she went on to act in the definitive productions of gnomic and disorientating work like Not I, Happy Days and Footfall. She was prepared to suffer for Beckett's art: for Play her face was a mess of glue and porridge; in Happy Days she was buried up to her chest in mud; and for her 1972 Not I she was deprived of sight and sound and strapped into a head vice. "It's seldom you have a relationship which covers such a vast canvas," she once said. "You have your friends, your husband, your children and your work – well, Sam was all of those to me."

Their rapport was cemented during the rehearsals for Play; she soon grew used to his punctiliousness, famously asking her to "make those three dots, two dots". She likened his directing to conducting: "He didn't have to say much. 'Don't act', which meant 'Too much colour', 'louder', 'softer', 'quicker', 'slower'. I remember once he kept saying, 'Slower, slower'. I said, 'If I go any slower, I'm going to bore them to death'." His reply was unequivocal: "Bore them to death. Bore them to death."

She and Beckett forged a remarkably symbiotic relationship. He was asked what made her so ideal for his plays. "She doesn't ask any damn fool questions," he replied. And Whitelaw was happy to bend to his will. "He used me as a piece of plaster he was moulding until he got just the right shape," she said, and would react indignantly if an interviewer dared suggest that the playwright was a gloomy type. She described him as "kind, warm, compassionate, with the most naughty twinkly blue eyes. I'm gloomier than he is." Their relationship was tested during the opening run of Not I. Whitelaw's son was ill with meningitis, and she broke down during rehearsals. "Billie," Beckett cried, "what have I done to you?"

Given the artistic demands made by Beckett and fulfilled with unerring precision by Whitelaw (during Happy Days she asked him in which direction she should be looking, and was told "Inward," a response she described as "one of the best pieces of direction I ever had"), it is remarkable to reflect that she suffered from stage fright right through her career. She came from a hard-up Coventry family – she was terrified by the air raids – and raised in Bradford.

Her father, an electrician from Liverpool, died of lung cancer when she was 10 – "I used to go to bed every night saying, 'Please God, let Daddy be dead in the morning. It was awful listening to him crying out in pain" – and she developed a stammer, which she tried to cure by going to a Saturday-morning theatre club.

There she was spotted by a BBC talent scout and she appeared in Children's Hour as Bunkle, an adventure-prone schoolboy, alongside such future talent as Beryl Bainbridge and Tony Warren, creator of Coronation Street. But she vividly recalled being sick before each recording. Much later, when she received her CBE from the Queen in 1991, she was so nervous she couldn't say a word.

She twice left her first husband, the actor Peter Vaughan, who she married in 1952, but went back because she didn't want to make him miserable. "Finally, he left me – that was the joke." She found happiness with the actor and writer Robert Muller, until his death in 1998.

After working with Joan Littlewood's Theatre Workshop, and a period in rep she joined the National Theatre under Laurence Olivier, playing Desdemona to his Othello. "It was like acting with the Rock of Gibraltar," she recalled. Then came the fateful meeting with Beckett.

She won a Best Supporting Actress Bafta in 1969 for her roles in the psychological thriller Twisted Nerve and as the ex-wife of Albert Finney's made-it-big-in-London Northern writer in Charlie Bubbles (she and Finney embarked on what she called "a mild affair").

In 1976 she was chilling as the evil nanny Mrs Baylock in The Omen, and in 1998 she was in the well-regarded wartime drama The Dressmaker, based on the novel by her former Children's Hour colleague, Beryl Bainbridge. "Billie Whitelaw's Margo is a blowsy, capricious creation that one would scarcely expect from our leading interpreter of Beckett," was The Independent's verdict.

In 1990 she was mother to the Kemp brothers' eponymous gangster twins in The Krays – a film for which she felt obliged to say, "I can only hope that young people seeing this film will realise that both the twins have said that nothing of what they did was worth what they have been through the past 20 years''

She did some fine work on television; one highlight was the 1997 series Born To Run, in which she played the downtrodden wife of an obnoxious businessman who undergoes a Shirley Valentine-like metamorphosis, jetting to Tenerife when he has a heart attack. "I can't remember when I had such fun in a role," she said, "but for me, at my age, to be rogered over the bonnet of a Jaguar..."

She spent some of her later years working for the organisation Victims of Torture, as well as performing Beckett at gala evenings and on lecture tours. She wound down her acting career, though she was in the Simon Pegg comedy Hot Fuzz in 2007. She spent her last years in a nursing home in Hampstead.

For all her achievements she never quite conquered her stage fright. "I've never really felt like a proper actress," she said in the 1990s. "I still feel like that six-year-old girl who was frightened when the bombs were raining down out of the sky in Coventry." And she told The Independent, "Death's not one of those things that frighten the life out of me. Getting up on stage with the curtain going up frightens me more."

Billie Whitelaw, actress: born Coventry 6 June 1932; CBE 1991; married 1952 Peter Vaughan (divorced 1966), 1967 Robert Muller (died 1998; one son); died London 21 December 2014.