Corin Redgrave: Double agent

The Duke of Windsor, George Washington, Julius Caesar, Jean-Paul Marat, Montgomery of Alamein, Edward Heath: Corin Redgrave has certainly covered the waterfront where playing prominent public figures is concerned. He's a particular master at getting inside real lives that were double lives. Oscar Wilde and Roger Casement are among his most haunting performances. Now, continuing in that vein, Redgrave is performing at the Minerva, Chichester in Blunt Speaking, his own one-man play about Anthony Blunt, set during the tumultuous days in 1979 when this doyen of the English art world, who had been Surveyor of the Queen's Pictures and a wartime MI5 agent, was publicly exposed as a former Soviet spy.

As he makes coffee for us in the kitchen of his south London home, it strikes me that Redgrave, who graduated from Cambridge with a First, would himself have made a good double agent. With his rather austere, donnish manner and punctilious, mandarin accent, he'd more easily pass as a pillar of the Establishment than as the still-committed and active communist who has recently started the International Movement for Peace and Justice in Chechnya and Artists Against Racism.

During our meeting he's courteous and sensitive, but there's an inscrutability about him that would, you feel, have appealed to those spy recruiters in Thirties Cambridge. Not that there's ever been anything covert or contradictory about his identities as actor and political activist. They have conflicted only in the sense of losing him work. Before the days of perestroika, his well-publicised affiliation to the Workers' Revolutionary Party, of which he was an organiser, got him blacklisted by the BBC and cold-shouldered by the Royal Shakespeare Company. Since emerging from the theatrical wilderness, he has gone from strength to strength, though last year he had to fight off a bout of prostate cancer.

When we meet, he's just finished playing Crocker-Harris in Rattigan's The Browning Version in an excellent Derby Playhouse production by Mark Clements. The role of the dried-up classics master who is disarmed into a paroxysm of uncontrollable grief by an unexpected present from one of the boys was immortalised on screen by Sir Michael Redgrave, Corin's father and patriarch of this great acting clan. In his moving memoir of him, Corin explains how he cannot watch that scene on film without being reminded of the night in 1967 when, having blurted out the secret of his bisexuality to his son, Sir Michael was convulsed by terrible, unrestrained sobbing.

I wonder whether the recollection has fed into Corin's own piercing performance. "No, I never consciously thought about it while I was doing it. The problem with using your own emotional memories in acting is that memories fade, and then there's something slightly masturbatory about the process because they cease to hold any validity. That's where Stanislavsky was wrong." He arrived at his version, he says, by working on the principle that "when you have to portray dreadful grief, the only way you can reach it is by furiously fighting against it".

The tricky Oedipal business of tackling a role previously played by his an adored father (some say he has come into his own since Michael's death) is a rare experience for Corin. They "crossed territories" on a mere handful of roles (including Macbeth and Frank Elgin in Odets's The Country Girl). But there is a different kind of paternal connection with his latest project. Sir Michael Redgrave knew Anthony Blunt in the Twenties at Cambridge, where they founded and co-edited a literary magazine called The Venture.

Miranda Carter's acclaimed biography of Blunt features a photograph of an unhealthy-looking lady reclining in a shaft of sunlight, clutching a painting. That's Blunt in drag in a picture that accompanied a Granta parody of Orlando, by Michael Redgrave and others. "They had things in common," says Corin. "Blunt was homosexual. My father was bisexual and at times lived in fear of exposure. They both had friends in the Communist Party, but neither of them joined, so they did not receive the political education the Party gave its members. It may sound odd to claim Blunt was politically naive. But I believe his politics came from the heart."

The key questions are: what did Blunt betray; to whom; and with what consequences? Carter's biography argues that it is impossible to determine whether or not the top-secret documents Blunt passed to Soviets during the war sent men to their deaths. Redgrave is exercised by a prior consideration: "What is treachery? It is perfectly obvious even to a non-communist that there can be moments in history when there is a far higher moral imperative than the national security of one's own country. What would one make of Von Stauffenberg, for example?" But the leader of the plot to assassinate Hitler was, unlike Blunt, neither living in a democracy nor in league with a foreign power. Redgrave counters that as a true communist, Blunt believed that the loyalties of working men and women should transcend country. Besides, we had no right to keep military secrets from an ally.

This is not the first time that art has addressed the subject of Blunt. In Alan Bennett's 1989 play, A Question of Attribution, the restoration of a Titian canvas in which new figures are discovered provides a parallel for Blunt's interrogation, during his period of immunity, by Secret Service agents hunting for Soviet spies hidden in the Establishment. The implication is that it's as futile to think you have cracked the enigma of Blunt by calling him a fake as it is to imagine that you have solved the mystery of art by correcting an attribution. The riddle of his treachery is further complicated by the doubleness of the Anglo-Irish ancestry that the novelist John Banville gives the Blunt figure who looks back over his life in The Untouchable (1997).

Redgrave's quarrel with these versions is that "they think Blunt's politics were a kind of posture". His own play is an antidote to this. Through a speculation about why Blunt was granted immunity in 1964 and a contrast between that and the broken promises of 1979, it plays ironic-reversal games with the idea of loyalty, and offers a vindication of the conflicted former spy. Some may find its conclusions tendentious, but the piece offers a plum role that should bring out the best in Redgrave. He's an actor who excels at suggesting turbulent complications behind an enigmatic mask. The way repression turns people into oppressors and the hideous cost of living a lie were powerfully brought home by his acute portrayal of the eminent elderly author who is forced out of the closet in A Song At Twilight by Noël Coward (one of whose lovers, incidentally, was Corin's father). And he's never prepared to simplify idealists. When, in 1994, he and sister Vanessa set up Moving Theatre Company in a bid to unite art and politics, he kicked off by playing an Anglican country vicar who preached support for the General Strike in The Flag and the Irish nationalist martyr, Roger Casement. Alongside the tortured conviction of the vicar, his portrayal of Casement showed you the self-indulgent obliviousness of the kind of Utopian who is blind to the problems at his own hearth.

What will true-blue Chichester will make of Redgrave's left-wing take on Blunt? It's not the obvious venue. There's a pleasing symmetry, though, in the fact that Corin is making his debut there now. The Festival Theatre is celebrating an anniversary. It is 40 years since the inaugural season, which was irradiated by the legendary Uncle Vanya of one Michael Redgrave.

'Blunt Speaking', Minerva Theatre, Chichester, to 10 August (01243 781 312)