To reach the age of 60, as Diana Rigg did in July, and still provoke a phwoah from a sizeable proportion of middle-aged males is an achievement itself in these Viagra-crazed days. Yet the fan club that gathered around Rigg after her portrayal of the cat-suited Emma Peel in the cult 1960s television series The Avengers is but one regiment in her army of admirers. She opened in the West End to rave reviews a week ago in Phedre, Ted Hughes's new adaptation of Racine's tragedy, and is making a return to the small screen in an occasional BBC series, The Mrs Bradley Mysteries.
For a woman who spent the early years of her childhood witnessing the last days of the Raj, it is quite an Indian summer.
Rigg has, of course, suffered the bungee-elastic highs and lows for which acting is notorious. When she was made a dame in 1994 the Queen asked at her investiture whether she was working: she wasn't. True, she had taken time out to raise her daughter - a burden after the break-up of her second marriage - but for long spells in the early 1990s she was virtually unemployed.
"It wasn't that I was going for parts and not getting them," she says. "I wasn't being offered anything at all. All actors go through quiet periods, but not many of them will talk about it."
As one of the most articulate actresses of her generation, Rigg will talk about almost anything, apart from her private life, which she has always protected fiercely with a Peel-style stiletto to the nether regions of the prurient.
She refused point-blank to sit "in the psychiatrist's chair" for Dr Anthony Clare, and says: "I will remain as private as possible until the day I die, which means I shall never write an autobiography."
She was born in Doncaster, South Yorkshire, but her family moved to India when she was two months old. Her father, an engineer, had answered an advertisement in The Times and went to work on the rail ways. She had an ayah, an Indian nanny, who taught her to speak Hindi, and she remembers sitting on her father's knee as he read her the Just So stories and The Hobbit.
Her father was a good shot and a keen fisherman, and fly-fishing has remained an endearingly unluvvie recreation. Trying on her mother's red chiffon dress one day, she felt a thrill of transformation that was the first stirring of the actress.
At eight she was back in Yorkshire, living in Leeds and attending school in nearby Pudsey. Her parents were not theatrical, and while she listened avidly to Saturday Night Theatre on the radio they played bridge. When they eventually took her to see Henry VIII she immediately asked to go again. Fortunately, a teacher shared her thespian passions, and, after her storming performance as Goldilocks in the school play, persuaded her reluctant parents to let her study at the Royal Academy of Dramatic Art (Rada).
Big-city life rather went to her head - "I left with a plain diploma, a pass, the minimum," she says - and her overtures to the Royal Shakespeare Company were rejected. She took a job instead as an assistant stage manager in Chesterfield, Derbyshire, prompting so vigorously from the wings in one production that the local paper suggested she should take a curtain call.
But by 1959 she had been accepted by the RSC, where she inevitably started as a spear-carrier, in A Midsummer Night's Dream. It was an extraordinary time to be at Stratford. Peter Hall had taken over as artistic director, and Vanessa Redgrave, Albert Finney and Rigg played walk-on parts around the towering egos of Laurence Olivier, Paul Robeson and Edith Evans.
Rigg progressed fast, playing Lady Macduff, Adriana in The Comedy of Errors, and Cordelia to Paul Scofield's Lear.
"A brilliantly skilled and delicious actress," noted Olivier. "Anyone who doesn't find her devastatingly attractive must be an Outer Mongolian monk," said Douglas Fairbanks Jr. "If she doesn't waste herself on silly films, she could become something good," said the doyen of directors, Peter Brook.
But at the height of her powers "silly films" were what she opted for, playing Emma Peel from 1964 to 1968. The role, as Patrick Macnee's seductive-but-deadly sidekick, brought her instant but sometimes unwelcome celebrity. At the Motor Show she had to hide in a lavatory to avoid being mobbed. The piles of steamy letters she received from adolescent males she passed on to her mother, who wrote back saying: "Those aren't very nice thoughts, and besides, my daughter is far too old for you."
Her companion for most of the 1960s was Philip Saville, the film and television director, but although she was an icon of the age she refused to conform to nonconformity: "There was a lot of rubbish going on on the sidelines. All that flower talk. I couldn't 'man' anybody."
The 1970s saw more stage successes with Tom Stoppard's Jumpers and Night and Day, and Ronald Millar's Abelard and Heloise, but in the classical repertoire Maggie Smith, Judi Dench and Vanessa Redgrave forged ahead. There were movies, but generally best forgotten - does anyone remember On Her Majesty's Secret Service, with George Lazenby as James Bond? In 1973 she had married Menachem Gueffen, an Israeli painter photographed unkindly in the tabloids with moustache, open shirt and medallion. They stayed together less than a year. All she has said about it is: "If it hadn't been entered into in haste, it might have worked; but then if it hadn't been entered into in haste, it wouldn't have happened."
After her marriage broke up she met Archie Stirling, a former Guards officer, Scottish landowner and businessman, and, aged 39, had a daughter, Rachel. She married Stir ling in 1982 and for a while family life took precedence over theatrical ambition.
"If it were said that I didn't fulfill my potential as a mother and a wife I'd be heartbroken," she once remarked. "But if it were said I hadn't achieved my full potential as an actress, I would understand the reasons why." Ever experimental, in 1987 Rigg starred in the Sondheim musical Follies, in which she sang the in controvertible if diction-testing line: "No one thought to query her superior exterior."
The second marriage broke up when Stirling left her for Joely Richardson, the model daughter of her contemporary, Vanessa. In the best greasepaint tradition, Rigg picked herself up and dusted herself down. "I'm not going to play the grieving divorcee with a tear- stained face," she said. "It's not a particularly good part, it has lousy lines and absolutely no laughs. It's also a very boring role to play."
She went to the tiny Almeida Theatre in Islington to play instead in Dryden's All for Love at Pounds 165 a week, and then produced one of the finest performances of her life in Medea by Euripides. Rigg has always maintained that acting is more than merely distilling experience, but the blend of passion and restraint she achieved in Medea - who kills her children to spite a wandering husband - left some observers wondering how much was derived from her own inner turmoil. An acclaimed role in Brecht's Mother Courage followed, together with a knockout performance in Albee's Who's Afraid of Virginia Woolf?
Perhaps her Yorkshire down-to-earthness is the secret of her durability. When she was a child, bread with jam and butter was never allowed before a slice of plain bread had first been consumed. As a young actress she realised she was on the road to success when she found a Pounds 1 note in her purse that was not accounted for. As a successful actress in The Avengers, she discovered that, at Pounds 90 a week, she was paid Pounds 10 a week less than the cameramen, and insisted that the rate be doubled. Although The Avengers is still shown in dozens of countries, she collects no royalties - financial mismanagement that evidently nags.
She seems to have a genial dislike of journalists, accepting lunch invitations from the better sort of wordsmith, while revealing relatively little. The tabloids she calls "grubbies" and she refuses to be interviewed by any female reporter - "grubbettes" in her parlance. "They are so mean," she says. "They continually play the sisterhood card. 'I'm a woman, too,' they say, 'and we have these things in common.' And then they abuse it so cynically in print."
Religious faith (Church of England) is another source of strength. "I don't accept all the tenets of the Christian ethic, not 100%," she says. "But belief is very important in my life. As I careened through late adolescence and my twenties and thirties it was always there...I'm slightly old-fashioned, love a sermon, love our hymns."
In a rare moment of confession, she added recently: "I'm slightly aghast that you see before you a twice-divorced woman. I'm shocked. It's not how I saw myself, how I imagined things would work out, not what I believe in."
Theatrically, at least, things have worked out a great deal better than they looked at the beginning of the decade. She still has the ambition to do a rip-roaring musical - she turned down a lead role with Lee Marvin in Paint Your Wagon when her father was diagnosed as terminally ill - and she is one of the few actresses who could carry it off and play Shakespeare on the side.
"We used to have actresses trying to become stars," Olivier once loftily remarked. "Now we have stars trying to become actresses." It's reassuring to know that, in Dame Diana, the two categories are as one.