GLENDA JACKSON was among the finest actors of her generation when, at 55, she left the stage and stood for parliament. Elected in 1992, she spent 23 mostly sterile years as a left-wing backbencher, best remembered for a bitter attack on Margaret Thatcher shortly after the former prime minister’s death. “A woman? Not on my terms,” Ms Jackson thundered. Watching her speech with hindsight, it is easy to detect a regal fury that could be an audition for Shakespeare’s “King Lear”.

Good female actors, sometimes frustrated by the shortage of meaty parts for them, are moving into the great roles written for men. London’s Donmar Warehouse is currently staging three Shakespeare plays acted entirely by a company of women, led by Harriet Walter. In 2014, Maxine Peake was a well-regarded Hamlet in Manchester’s Royal Exchange Theatre. After Ms Jackson left the House of Commons, she was tempted back to the stage at the age of 80 by seeing Núria Espert, a celebrated Catalan actress, playing Lear.

Every ambitious actor feels compelled to attempt this Everest of roles, a tragedy of old age and betrayal, and madness and cruelty. The part requires the widest range of emotions imaginable. Lear expects to have his own way, and his temper rages when he does not get it. (There may be an element of typecasting in Ms Jackson’s case.) Ms Jackson’s decision to tackle the part has been the talk of the London theatre: Did she still have the stamina? Would she look like a man, or a woman?

She dresses in a woman’s cardigan and black trousers, and occasionally a fetching red coat. When, in Lear’s madness, she takes off her trousers, she reveals spindly thighs. But there is still strength in her unmistakable voice, and she has the energy to sustain the three-hour performance with power and precision. Lear’s rage comes naturally to her, but there is a moving softness and humour in her mad scenes. What is missing is the depth of emotion at Cordelia’s death, which ought to have the audience in tears. But critics have generally been impressed.

Deborah Warner, the director, anchors the play in the present. Lear’s court sits on blue plastic chairs, and the background noises include a reversing lorry. The Duke of Albany carries the Spectator, a shopping trolley makes its now almost obligatory appearance, and Lear’s Fool is dressed in a ragged Superman outfit. When Gloucester’s eyes are gouged out (by an electric drill) one of the eyeballs is thrown into the audience, provoking nervous laughter at precisely the wrong time for a theatrical joke. Some of the verse is garbled, and the noisy storm made by billowing black refuse bags drowns Lear’s “Blow winds, and crack your cheeks.” Not all the performers rise to the occasion, but what really counts is Glenda Jackson’s compelling start to the last act of a dramatic life. In a memorable comeback, she commands the stage.