With Mrs Brown, the story of Queen Victoria's relationship with the High- land gillie John Brown, she got both - the movie and John O'Groats (or at least locations across Scotland). This might explain something because, extraordinarily, this is her first feature-film lead. There have been supporting roles - A Room with a View, Henry V, A Handful of Dust - but generally she has shied away from cinema.
"With film I don't feel on sure ground," she says. "When it's done it can't be improved - with theatre you go on till you get it better. It is a work in progress." She doesn't mention that, more than 30 years ago, when she emerged as an instant star of theatre, having gone straight from drama college to be John Neville's Ophelia at the Old Vic, she was dismissed as unsuitable for the big screen. "Miss Dench, you have every single thing wrong with your face," she was told apparently.
But now, Mrs Brown, a small-budget British feature - pounds l.5m, 33 locations in 30 days - has been hailed in Cannes and, more importantly, in the America. When it opens here next month, she will be busy even by her own prolific standards, starring at the National Theatre in David Hare's new play Amy's View, repeating her unlikely role as M in the new Bond movie, and preparing another series of As Time Goes By for BBC1 television.
On screen in Mrs Brown, the face that journalists liken to that of a Persian kitten fits Queen Victoria's widow's cap to a T. This is not a role for a vain woman, says Dench, rather grimly. The rasp in her Tallulah Bankhead voice heightens the "tremendous waywardness" she was pleased to find in Victoria. In the flesh, giving interviews in a London hotel, she's prettier, dressed in floating white and heavily be-ringed. Twice burgled, she now wears all her jewellery.
Mrs Brown explores the relationship, unlikely enough to be intriguing, that pulled Victoria out of the depression into which she had slumped after her husband's death. It was, Dench says, "a passionate, cerebral relationship of the sort it's difficult for us now to understand. Difficult then, too, it seems. In the 1860s, cartoons showing John Brown on the throne or describing the Queen as "Mrs Brown" circulated in pamphlets and magazines. "She must have known, mustn't she?" says Dench.
Relevance to our own royals was not, Dench says, much discussed on set. True, the Royal Family successfully protested against an earlier script on the same subject, but times change and the moral high ground becomes increasingly untenable. And Mrs Brown is not, in any case, a story of adultery.
"I never believed there was a sexual relationship between them, but we'll never know," says Dench. "That's not what the film sets out to show - much though I'd like to have flayed about in a bed with Billy."
Billy Connolly, with hair and exuberance toned down, is an unexpectedly convincing John Brown. He raves about Dench's raunchy sense of humour, and she talks of him ("a hero of mine for his comedy") with real enthusiasm. Does she draw a lot from her fellow performers?
"Absolutely. I suck them dry. To me it's the difference between being a director and an actor. My husband is about to do an adaptation of Aubrey's Brief Lives - all on his own!" She says it incredulously.
Dench has been married to Michael Williams, the actor, for 25 years. "I said to Michael, 'Do you see a vestige of Billy Connolly in his performance?' In parts you almost hold your breath. He's such a good actor. Unflappable." (This last is a serious accolade from the unsentimenatal Dench.) "He's a deeply serious man. People fall into the trap, when they meet him, of expecting he's going to be funny all the time. Maybe they feel the same about me."
She doesn't mean that they think she should be funny but that she should conform to the image that they have of her - "cosy", as she describes it. Ten years ago, I interviewed her in the pretty, painting-filled Hampstead home that so famously burned down. She complained then about people's expectations. "There is something of every part you play within you. A whole kaleidoscope - fierce emotions - so why do people just take the colour you play on top and label it homely?"
I remind her of this, and she says she doesn't think the problem has disappeared. It seems perverse for the public to isolate the quality of cosiness from a woman who has played Lady Macbeth, Cleopatra and Mother Courage but the trouble is Dench's famous and genuine niceness. It's something from which you can never get away. Ten years a Dame this winter and you can't even accuse her of feeling smugly secure.
"You take each job and it brings a whole new set of nerves. I think I get more nervous as time goes on. You find a way of sublimating it, of channelling it into the performance. I think I'd be worried if the nerves went away."
Suddenly I get a display of them. Mrs Brown is already tipped for next next year's Academy Awards ... "Don't!" she interrupts dramatically. She has had enough of that in the States, where she has been publicising Mrs Brown among the same people who made her see "the whole of 40 years' work sliding straight down the plughole" when they asked her what she had done in her career before playing M in Goldeneye.
The gulf between high and popular culture (along with "the theatre, what is real and what isn't, and the different turns that love takes") is a theme of Amy's View. But Dench seems to straddle it effortlessly. A line from the play comes to mind: "No roles for women!" cries her actress heroine, Esme. There's not much evidence of that in Dench's career, which has been one of infinite variety. She was 61 when last year she won the Olivier Awards for best actress in a play (Absolute Hell) and best actress in a musical (A Little Night Music).
A week after the interview I follow Dench's dresser through the blue rabbit warren that is backstage at the National Theatre. She is generous with invitations to her dressing room. There have been four visitors already today - it has been as many as 18, her dresser tells me - even though, minutes before, her performance in Amy's View was powerful enough to draw "Bravos!" at a weekday matinee. There is a paper lobster on the wall, and a card to a doting granny. Bond's M seems miles away.
It was Michael and their daughter Finty who insisted she should play M, she says. "I'm not good at choosing. It's better for someone else to see you in their mind's eye."
The role made her a name in Middle America, the transatlantic equivalent of what happened long ago when she did Z Cars after a run of triumphs at the Old Vic and workmen in the street started spotting her. "Yes..." she says, remembering, and making it sound like an admission. "I do like that, really."
'Mrs Brown' (PG) goes on general release on 5 September.