Last Summer, Penelope Wilton was at the Almeida theatre in David Hare's masterly production of Heartbreak House when she received a card from a man she'd never previously worked with. "It was from Alan Bennett saying he'd written this piece and could he send it to me? He did so, saying `if you like it, perhaps you'd like to do it ... I shan't mind at all if you don't'. I said I'd love to."
That, clearly, is putting it mildly. Months later, seated hidden away in the corner of a deserted Kensington hotel on a Sunday night, you can tell she's still quietly thrilled that he asked her to play Rosemary, the sole character in Nights in the Gardens of Spain, one of the hungrily awaited second series of Talking Heads.
Ten years ago, senior television dignitaries who should have known better did a lot of headshaking when the first series was suggested. Even the Rolls-Royce names of Thora Hird, Patricia Routledge, Julie Walters, Maggie Smith, Stephanie Cole and Bennett himself couldn't convince some pundits that monologues to camera would make riveting television. How wrong they were. Endlessly repeated, they have been sold across the world and been translated on to video, audio tape and even on to the stage.
Next month, the new series begins with Patricia Routledge and further returns by Thora Hird and Julie Walters, plus debuts from Eileen Atkins, David Haig and Penelope Wilton. But you can first see Wilton in tomorrow night's BBC2 film This Could Be The Last Time.
It was the surprisingly subtle emotional range of George Day's script - half-romantic comedy, half chase-thriller - that persuaded her to play Marjorie, the sensible, put-upon daughter of Joan Plowright. When mother goes AWOL in Paris, Wilton gets to do what she does particularly well on screen: worry.
There's a very beautiful scene in a police cafe where she is sitting with a charming French detective talking happily about her childhood. The camera rests on Wilton's upturned face as she talks of her parents' early expectations of her. Her head drops and you suddenly see her feeling the loss of her missing mother. As she looks up, the smile and both cheeks have dropped in pain. It's film acting of a very high calibre; the sort of thing which must have attracted Bennett.
That quality of performance is built not only imaginative sympathy but real cinema technique, both of which are put under intense pressure in her Talking Heads play which was filmed in one 12-hour day.
Unlike television, which tends to be shot on several cameras and cut together, this is on film, i.e. one camera, but with very long, almost theatrical takes lasting for minutes on end. She laughs at the memory of being word-perfect and then falling at the final hurdle which meant starting all over again.
"We'd do a take and Alan would be round the corner with Mark Shivas, the producer, watching on a monitor and he'd come round and say, `I knew, it, you were getting to the end of the take and I was stuffing my handkerchief in my mouth hoping you'd get there ...'"
On most productions, editing means that slip-ups and dropped words can be spliced in, but with something as exposed and tightly well-written as this, you can't. "You know immediately if you've said the wrong thing because the rhythm has been broken, so you just have to go back to the beginning again."
Although ideally the viewer is unaware of the problem, the most complex decision for the actors in these plays is their relationship to the camera. "The tricky thing is how much do you talk to the audience as if talking to a friend and how much is actually to yourself? How much are you looking directly into the camera and how much do you reflect back to yourself. It's the same in conversation ... you don't always look straight in the eyes of the person you're talking to."
Wilton strongly believes that for work like this, one has to feel there is another person there. "One has to engage with the audience and you do that by having a strong relationship with the camera. It's not about just doing it and oh, by the way, there's a camera watching you. You really have to take the camera in. Otherwise it becomes disengaged."
Not that she's ready to relinquish everything to the camera. "Your performance has to be energised, you have to keep it going," she says. If you leave that to clever editing, it takes away from the writing and the piece."
She and her director, Tristram Powell, were given a pretty free hand. The script had no camera or stage directions and it was up to them to find natural breaks and scene changes. Bennett came along to a run-through quite late on in the proceedings.
"A bit nerve-wracking," says Wilton, understatement being the order of the day. "He was very sweet because, although we were only in a little room, he tried to keep out of my eyeline. But you're still aware that he wrote it and you could completely mess it up at any point. But he was very encouraging."
Like opera singers who learn their roles before rehearsals, Wilton arrived with the part committed to memory. Did that mean she had to struggle with re-writes? Apparently not. What she first saw is what we'll now get ... except that it turns out that Bennett wasn't too sure of his plants.
"We had a climbing magnolia at one point until someone told him that magnolias don't climb ... and I asked to change the word "kiddies" to children because kiddies is a northern expression which sounded wrong coming out of me." He'd already told her not to worry about any accent. "I want you doing it," he said.
Which is what Bennett has got although she refused to check the progress of her performance during the shoot. "I never watch playbacks on monitors, though there is something to be said about going to the rushes when you're filming over a long period," she says. "Things are shot so out of sequence, it's good to have that sense of where you're going, but with this happening over one really concentrated day you just go for it."
In fact, in common with most actors who physically recoil when seeing their own work stuck in aspic on screen, she wasn't even going to watch the finished film.
"I can't look at myself critically. Vainly, I always end up thinking, "Oh dear, that jumper ... you know, all those sorts of things ... you're so astounded by seeing yourself." But then realising that she would be away when it is to be finally transmitted, she watched it discreetly on her own.
"I was taken up by the fact that it's a really good story and it didn't really look too much like me ... it seemed to be somebody else. That doesn't always happen. I was rather pleased by that."
`This Could Be the Last Time' is on BBC2 tomorrow. `Talking Heads', also on BBC2, begins on 6 Oct