Sheila was born in Chard, Somerset. After attending Howell's school, in Denbigh, Clwyd, she trained at the Royal Academy of Dramatic Art from 1949 to 1951. Repertory seasons followed, first in Yeovil and Pitlochry and then for the Arena theatre company in Birmingham, where her roles included Katherina in The Taming of the Shrew and Beatrice in Much Ado About Nothing. From Birmingham she moved to Bristol Old Vic which, in the late 1950s, was the most prestigious of rep companies. There she played in Shakespeare, Shaw and once-fashionable contemporary plays such as Peter Ustinov's Romanoff and Juliet.
It was in London in January 1962 that Sheila caught the all-important eye of the Observer's drama critic, Kenneth Tynan. Reviewing the whimsically titled On a Clear Day You Can See Canterbury, at the Theatre Royal, Stratford East, Tynan described her as "a new actress of explosive charm and authority with a tough, pouting presence that banishes cuteness and even encourages awe". Writing about her again, four months later, in James Brabazon's The Last Ally at the Lyric Hammersmith, Tynan became even more fervent, hailing "a troubled, big-boned, life-illuminating creature called Sheila Allen" and adding: "I am tempted to place her on the shortlist of postwar actresses to whom I might one day append the adjective great."
Even if greatness may have eluded her, Sheila was always brilliant at playing women of strength, wit and charm. Her marriage, in 1964, to the stage and TV director David Jones, guided her career towards the RSC, where Jones became an artistic associate. She appeared, under his direction, in David Mercer's Belcher's Luck (1966), earning great praise for her portrayal of the haughty, English upper-class Helen Rawston. At Stratford, she had a voice and a presence that could command the intimidating main theatre but could also be modulated to suit the demands of the intimate Other Place.
Sheila twice played Goneril in Stratford King Lears: for Trevor Nunn in 1968 and for Buzz Goodbody in 1974. I also recall her as a memorable Constance in John Barton's 1974 version of King John, where she turned a woman who often seems a Niagara of self-pity into an awesome icon of grief. But it was Gems's Queen Christina, first seen at the Other Place in 1977, that gave her the role of a lifetime and enabled her to inspire comparisons to Garbo in her ability to capture the cross-dressing monarch's sexual ambivalence and inner contest between desire and duty.
As if to escape the clutches of institutional theatre, and to assert her feminist independence, Sheila often appeared in the emergent London fringe of the late 1960s. I have a vivid memory of her as a whip-brandishing dominatrix in a show called Vagina Rex at the old Arts Lab in Drury Lane in 1969.
The pattern of her career was partly determined by her husband's movements. When was invited to form a permanent rep company at the Brooklyn Academy of Music in 1980, she became a pivotal member of the team. She was particularly fine as Paulina in a Brooklyn production of The Winter's Tale, savagely clawing Leontes's attendants and at one point staging a sitdown protest in his bedroom. She returned, with Jones, to London to appear in 1987 at Hampstead theatre in Richard Nelson's Between East and West where she appeared, opposite John Woodvine, as a Czech exile viewing American life with an enthralling mixture of pride and prejudice.
Sheila acted periodically in films and on television, most notably in The Prisoner in 1967 and as Cassie Manson in Bouquet of Barbed Wire (1976). In the latter, the intensity of the relationship between her possessive husband (Frank Finlay) and manipulative daughter (Susan Penhaligon) came to be mirrored in her involvement with her son-in-law (James Aubrey). The following year saw a sequel, Another Bouquet. But she was, essentially, a stage animal and, when not acting, showed herself to be a born teacher.
She taught at the Lee Strasberg institute in New York and, more recently, at the Guildford School of Acting. To my astonishment, she turned up a few years ago in a text-and-performance degree class at King's College London, where I was lecturing. I should not have been surprised: Sheila was not only a superb actor but also a passionate, intellectually voracious woman always driven by a hunger to learn.
She is survived by her sons, Joe and Jesse. David, from whom she was divorced, died in 2008. A sister, Joan, also predeceased her.
Sheila Allen, actor, born 22 October 1932; died 13 October 2011.
Sheila Allen with James Aubrey in Bouquet of Barbed Wire (1976). She was, essentially, a stage animal (photo: ITV/Rex Features)