Diana Rigg kicking ass while clad in a skintight leather catsuit as Emma Peel in The Avengers is one of the swinging sixties sexiest, if quintessentially British, iconic images. That particular image, however, as a wonderfully stern Dame Diana is at pains to point out in between performances of Tennessee Williams's Suddenly Last Summer, was a very long time ago. Even the sad lad TV geeks who get their kicks watching Rigg as Emma Peel on endless re-runs of this most stylishly camp of spy shows must admit that time has moved on.
These days, as well as her actual honour, Rigg is a fully- fledged grand dame of the theatre establishment, picking up major awards for recent turns in such heavyweight material as Who's Afraid Of Virginia Woolf?, as well as the title roles in Medea and Phaedra Britannica. In real life, too, she cuts a formidable figure, whether in a more formal role as chancellor of Stirling University, or else protecting herself from some of the press's more cut-throat attributes by successfully suing one national newspaper last year.
In Suddenly Last Summer, Rigg plays Mrs Venable, an altogether more physically frail creature than herself. Onstage, however, she remains fierce to the point of hectoring in her attempts to enforce a lobotomy upon the young woman who looks set to out Mrs Venable's molly-coddled son as a predatory homosexual devoured by the young boys he once preyed on.
Caught inside a big venus fly-trap of a set, it's a towering performance, and where others of her stature might attempt to graft some kind of self-centredly glamorous veneer on to the character, Rigg is brave enough to leave herself exposed to a less flattering light.
Michael Grandage, director of Suddenly Last Summer, suggests she has "no vanity onstage whatsoever, and that allows her to go to a formidable place many actresses, particularly those of her generation, wouldn't dare go to".
"That's not," Rigg chuckles about the suggestion she might have preferred to opt for something more glamorous, "the world I live in. That would be too easy, and I'd much rather have a challenge. It would be easy to play Mrs Venable as some self-indulgent old bat with a screaming queen for a son, but the audience wouldn't believe all that hysteria, and, more importantly, I wouldn't believe it either. The biggest challenge for me is to go on stage and present this woman whose love was all-encompassing, and whose belief in her son's creative powers was total. Now that's very honest of her. She's a perfectly honest woman, who truly believes in this myth of her life."
Somewhat resplendently holding court in the theatre bar, clad in sloppy cream polo neck as far from Emma Peel as you can imagine, Rigg is fully aware of the power of myth to confuse truth in her chosen profession. Which is probably why she'd rather archive her own glamour- puss past, despite 2000's Bafta celebrating the role. And why not? By the time she took over from Honor Blackman as Patrick Macnee's impeccably apparelled foil in The Avengers, Rigg had been a successful stage actress and doyen of the Royal Shakespeare Company for a good half decade.
Even then, spikiness had become a stock in trade of sorts in roles such as Cordelia, the monarch's headstrong daughter in King Lear. Odd to think now, but Rigg's peers were initially sniffy over her move into TV full time following an appearance in the seminal Armchair Theatre.
"It was a very old-fashioned attitude," Rigg says, "in that theatre people were supposed to do theatre, TV actors were supposed to do telly, film stars remained film stars, and never the twain shall meet. I'm not giving myself any credit for changing this attitude, but I thought it was rubbish, and that I should be able to move between mediums and work wherever I wanted to."
By the time they welcomed the former ingenue back with open arms after only a year with The Avengers, they had a fully-fledged star on their hands, who continued her ascent as a Bond girl in On Her Majesty's Secret Service. As unsung as this was compared to the rest of the series, you could sense even then that Rigg wouldn't be happy settling for such out and out froth.
"I could've made a choice," she says, "at a certain time of my life to perpetuate a certain image of myself. I deeply admire the women who've done that, because it requires so much energy and discipline and single-mindedness, but," she shrugs, "I can't be fussed."
Such lack of airs and graces may have something to do with her roots in Doncaster, an archetypal grim-up-north town from which the young Diana Rigg was transplanted to India aged two months, but which clearly left something in her blood. Eventually returning to Yorkshire to finish her schooling, she first appeared onstage aged 13 in a school production of Goldilocks. By the time she started an acting course at RADA, Rigg had worked as a clerk, a telephonist and a fashion model. More significantly, this statuesque young woman was already adept at speaking her mind. Such a penchant for non-aligned rebellion almost resulted in her expulsion from drama school. Talent of a questioning kind, however, won out over the shyer souls in class.
It's similarly quiet types Rigg is perhaps thinking of when she attends graduation day lunches at Stirling. "I'm not as active as I could be," she admits, "and I'm sorry about that, but it's one of the perils of being a working actress. It's still a big responsibility. Someone said to me that a student will never forget who gives them their degree, and that makes my role as chancellor very dear to me."
You certainly can't imagine Rigg's daughter, actress Rachael Stirling, being such a wallflower during her own training. She, too, caused something of a small-screen stir in the music hall raunch of Tipping The Velvet. Typically, Rigg was nonplussed by the fuss, and, as last year's case, caused by the ludicrous allegation she had little time for British men or some such rot, which she won unequivocally, proved, some areas of the press aren't to be trusted.
Rigg has previously offered more light-hearted, less financially damaging digs at those by whom she's judged. In 1982 she edited No Turn Unstoned a compendium of some of the world's worst theatre reviews ever published. This may be considered a more civilised alternative to her 1973 role in the camp schlock horror pastiche, Theatre Of Blood. Here she played the wife of a wonderfully hammy Vincent Price, an old luvvy exacting merciless revenge on the self- aggrandising hacks who ever gave him a bad review.
Rigg has suffered precious few such slings and arrows over the years, and carries the first half of Suddenly Last Summer with a matronly but nonetheless scarifying grotesque gravitas. While it later becomes Victoria Hamilton's play, quite magnificent as Catharine, the young doll-girl full of crumpled elegance and guileless honesty forced to defend herself, watching Rigg wither is electrifying.
"I don't see Mrs Venable as unlikeable or I'd play her another way," Rigg insists. "I understand where she's coming from. I understand her need to keep the image of her son clean, or else, how else is she going to live her life?"
Of Grandage's observations concerning her own bravery, Rigg is typically nonplussed.
"Vanity in a 65-year-old is slightly misplaced," she says after pause for thought. "and I am, after all, a crumbling woman." With or without black leather catsuit, Diana Rigg still kicks.
Suddenly Last Summer is at the King's Theatre, Edinburgh, March 9- 13.