At first, I think that Susannah York has arrived for lunch with her own ready-packed meal. Her bag is bulging. But that's not her food. It's her dog. An eight-week-old terrier called Oscar peeps through the zipper. Dog and owner are interestingly coiffed: Oscar has a mass of tangled white ringlets; Susannah, a spiky blonde arrangement, like a tamer version of Rod Stewart's barnet.
Still, she retains the dazzling smile and bright blue eyes of her youth, and now, in her early sixties, she is no less a beauty than she ever was. York has managed an intriguing journey from the early days of film stardom in Tunes of Glory (her debut, in 1960, with Alec Guinness and John Mills) and Tom Jones (with Albert Finney) to a busy schedule of writing and stage acting. "You have to remake your life as you grow older and out of fashion," she says, without a trace of bitterness. We are meeting at the Croydon Warehouse, a welcoming fringe venue where York is rehearsing a new mystery thriller, The Kindness of Strangers, by Sara Mason. All York will say is that she was so fascinated by the script that she accepted it despite being perilously busy. Two conditions: that Oscar would remain with her at all times (though not on stage in performance - well, not so far, anyway), and that she could have four days off from rehearsal to go to Israel and support the anniversary of Mordechai Vanunu's "so-called release".
Vanunu, the Israeli who blew the whistle on his country's illegal nuclear weapons production at the place of his employment, handed over drawings and photographs of the installations to the Sunday Times in 1986. Kidnapped by the Israeli authorities, he was sentenced in a secret trial to 18 years in prison, 11 in solitary confinement. Released on 21 April 2004, he is now being accused by the Israeli government of being in breach of his "parole" and is not allowed to leave the country.
Four years into the sorry saga, York was asked to perform at a Vanunu benefit evening, and she has remained close to his cause ever since. "I am against nuclear weapons, and all weapons of mass des-truction, on every ground." Was she a member of CND in the 1960s? She was, and she tilts her left hand to reveal the metal CND ring she has worn for decades. This week on the plane to Israel, York will be taking the first draft of a screen version of one of her own children's books, In Search of Unicorns. She has another screenplay on the go and is always in demand for her luminous solo show, The Loves of Shakespeare's Women. Having first performed it at the Edinburgh Festival in 2001, she has taken it all over America, not to mention festivals in Adelaide, Georgia and Budapest. Her "excerpted" heroines include a skittish Beatrice, a sensual Cleopatra, a blood-curdling Lady Macbeth and a savage Margaret of Anjou. You would pay good money to see her in all of these roles. But although she had a spell at the Royal Shakespeare Company as one of the Merry Wives and an elegant Gertrude (to Alex Jennings's Hamlet) eight years ago, she has not scaled the classical heights. Her 1982 Hedda Gabler was a husky mezzo, but not wholly successful.
Interestingly, she finds Shakespeare more rewarding now that her own life has encompassed a series of loves, losses and periods of estrangement and reconciliation. She saw little of her father, who was divorced by her mother when she was five, until the last ten years of his life. Her elder sister, who died in 1985, was a heavy drinker, and a last-minute pact never compensated York for years of separation. And her marriage to fellow Rada student Michael Wells ended in 1976. Their children, Sasha and Orlando, are both actors.
Apart from the children, I wonder, who means most to her now? "I have a male companion of many years standing. I have a room in his house, he has one in mine. But there's no romance in my life, if that's what you mean . . ."
Oscar has fallen asleep. A good, honest plate of Croydon Warehouse quiche and chips has been gustily consumed, and it's time for the afternoon's work. My day is made by a peck on each cheek from that glorious great gash of a mouth and a darting farewell. Oscar is stuffed back in his bag and smuggled away to the rehearsal room.
The Kindness of Strangers is at the Warehouse Theatre, Croydon (020 8680 4060) from 29 April to 22 May. For more on Mordechai Vanunu, go to www.vanunu.freeserve.co.uk