Situation comedy on British television is littered with the bodies of straight actors who died trying to raise a laugh. The female odds may be slightly better (both Penelope Keith and Wendy Craig made it from 'legitimate' theatrical backgrounds). However, it still takes a certain amount of courage for a classical actress to risk her artistic life across six original half-hour television scripts played out in front of a studio audience who would usually prefer to previewing a familiar series in which they already knew where they were supposed to laugh.
But then Diana Rigg has seldom been bereft of courage either in public or in private: she once got her Avengers salary trebled by the simple device of telling people what it was , at a time when such subjects were supposed to be sacred and secret, and her career thus far is a testimonial to the theory that if you stick your neck out far enough it may end up in something interesting.
And now, at 38, she belongs in the midst of that distinguished group of actresses (Glenda Jackson, Sian Phillips, Vanessa Redgrave, Janet Suzman, Maggie Smith) who manage to make the showbusiness establishment thoroughly uneasy: as a nation we still expect our female players to be glistening ingenues or lovable old ladies, which means that from her 30s to her middle 50s the most any actress can hope for is the occasional nervous suggestion of a repertory Hedda Gabler or an even more familiar Play if the Month.
All of which may go some way towards explaining why most of the above-named ladies have taken their career into their own hands and gone down some eccentric paths to preserve themselves from predictability; one of the places where those paths converge is, curiously enough, The Morecambe and Wise Show on which they've nearly all stooged at one time or another.
It was for Morecambe and Wise, a year or so ago, that Diana Rigg played her immortal Nell Gwynn in one of Ernie's searing dramas of historical folk, a performance which led the BBC to think that there might be a comedy series in Miss Rigg. The idea had in fact occurred to an American television network four years earlier and the result (a series called Diana) was a disaster on such an epic scale that Miss Rigg still cannot think of it without giggling.
Undeterred, and realising perhaps that there was nothing wrong with Diana that 18 British writers couldn't put right, the BBC has now come up with the idea of a six-week series called Three Piece Suite (a title supplied, incidentally, by Peter Barkworth to whom it was worth a bottle of Corporation champagne), the first of which will be broadcast on Tuesday.
What we have here are groups of sketches, three per week, all involving Miss Rigg alongside differing but distinguished co-stars ranging from Mr Barkworth through Tony Britton to John Cleese and George Baker, and all under the direction of Michael Mills. The writers of these ten-minute sketches include not only such BBC comedy stalwarts as Esmonde and Larby (The Good Life) and Clement and La Frenais (The Likely Lads) but also humorists (Alan Coren), playwrights (Keith Waterhouse and Willis Hall) and journalists (Jilly Cooper, Tona Brown), and it was the sheer variety of the talent involved that first appealed to Miss Rigg:
"I was in Vienna last autumn filming A Little Night Music with Elizabeth Taylor [whom she parodies in Three Piece Suite] and an awful lot of other ladies when these scripts began arriving and I knew then that they had to be done. Favourites? Not really, it depends in the end on which the audience like, but among the ones I've most enjoyed doing have been two Coward parodies (of Brief Encounter and Private Lives) by Waterhouse and Hall; then there's a 12-minute monologue which Hugh Leonard wrote for me and which I managed to do without cue cards, so I'm rather proud of that. Then again, there's a lovely adaptation of an old Alexander Woollcott short story which may or may not work out."
Miss Rigg is not a great believer in over-selling the product before viewers get it into their homes: "Obviously some of the sketches aren't as funny as I might have hoped, just as others are much funnier - and I'm still not happy with the old showbiz convention whereby I have to open every show as myself welcoming the guests; I'd much rather go straight into the first sketch with just a title caption. But there are still some old laws of television you apparently are not allowed to break, so there we are."
Not many rules are left standing so firmly in Miss Rigg's wake, though (or, perhaps, because) she comes of an extremely straight middle-class background. Born in July 1938 in Doncaster where her grandfather once ran the Co-op, she was the only daughter of a civil engineer who moved his family to India when he became manager of the state railroad there. Back in England she went to a succession of boarding schools ("Classes were incredibly boring. I took to dreaming. They took to punishing me") and then at 16 auditioned for RADA.
"I was a podgy, adolescent Titania but they seemed to think they could do something with me. Sian Phillips was there in my time and Finney was our leading light, but I sort of plodded on, too tall (five feet nine) for the juvenile leads and too hopeless to be a leading lady. Then I got some repertory work at Scarborough and Chesterfield and eventually I got to Stratford in 1959 where I was too tall to be a fairy in Charles Laughton's A Midsummer Night's Dream but all right for a Volsci in the Olivier Coriolanus."
Peter Hall was then just about to take over at Stratford and form the first permanent company there, one which he invited Miss Rigg to join on a three-year contract:
"That was a marvelous time for me - everything that school should have been and wasn't. We had movement classes, voice classes, fencing classes, everything classes, and there was a real family feeling."
With the RSC Diana Rigg rose from crowd work to Cordelia: then she left. Why?
"It was all getting too safe, too familiar, I just knew I had to leave and work with people who didn't still remember me as an apprentice. At first all I could was a job reading short stories on Canadian radio, so I did that for awhile and then The Avengers came along. I never found out why they chose me: maybe I looked good in black leather - it always seemed like Doomsday at Boreham Wood studios. But I loved it - The Avengers got me out of that classical Stratford mould forever, and it was all about the danger, which I liked. One must keep hazarding things - everyone plays so bloody safe now.
"I'm a great believer in doing everything your appetite tells you to do: I don't understand the piss-elegance about certain roles being 'unsuitable' or 'unwise'. Remember Gieguld halfway down a slide at Chichester in Caesar and Cleopatra a few years ago> That was a tribute to the man's fearlessness on stage and we should all remember it. Olivier, too, takes your breath away whether he's risking Coriolanus or a commercial. It's no good worrying endlessly about reputation - once you know what you are worth, it doesn't matter a damn what others think.
"But television is still terribly slippered, terribly safe: it's great ingredient is continuity, whether in The Avengers or now in Starsky and Hutch, seeing regular familiar characters in roughly the same set-ups week after week. With Three Piece Suite each sketch is a new beginning, and if the series works then I hope maybe we'll do another which goes deeper into satire and political parody. But I'm an actress, not the kind of funny lady who can ad lib jokes, and therefore I've got to be accepted in each sketch as a believable character. And that, at a rate of three a week, isn't easy: but at least we've got the kind of writers we need. When I did the American series all we had were three very small misogynists called Artie, Artie and Arnie, and Arnie would bring his golf clubs onto the set each morning and practise putting while the desperation grew."
But however well Three Piece Suite works out, there's unlikely to be another set for quite some time: Diana Rigg soon goes back to the National Theatre (where her three real successes so far this decade, Jumpers, The Misanthrope and Phaedra Britannica all started) to do Cat on a Hot Tin Roof for John Schlesinger.
Beyond that, it's anybody's guess: Miss Rigg's private life currently consists largely of an ex-Scots Guards officer called Archie Stirling (an eight-year friendship with the director Philip Saville and a tempestuous one-year marriage to the Israeli artist Menachem Gueffen now belonging firmly to her past) but professionally she remains a loner:
"If you try to plan a career the result is utter boredom for everybody: but it would be nice to think that there were still some conventions waiting to be exploded."
When Diana Rigg drove away from our lunch she was at the wheel of a white Mercedes with her initials at the number plates: somehow, that seemed about right.