Welcome to the double-edged world of Talking Heads 2. Writer Alan Bennett has created a whole world peopled by characters who say one thing but mean another. "Double-meaning" could be the motto of Bennettworld. As Mark Shivas, the series' producer, puts it: "Very often, you realise that the character you are watching is not what you thought and they slowly emerge in a very different light."
Some people have wondered how Bennett, now a well-off writer, can continue to tap into these mainly lower-middle-class characters. But Julie Walters, perfectly cast as the obsessive Marjory in "The Outside Dog", this week's contribution to Talking Heads 2, has no doubt: "He still lives up north where he's in touch with a lot of these sorts of people. He must soak up their language like a sponge. Also, he gets a lot of deep inspirations from his childhood, which is such an intensive, formative time. Sometimes, when I'm acting, I think, `Oh, I've picked that up from so and so'. It's the same when Alan's writing."
Walters refutes the image of Bennett as a comfortable writer. "There is this image of him sitting in nice Harrogate hotels having tea and talking about cardigans, but it's wrong. He's not cosy."
In fact, she says, he is a writer of darkness and complexity, and Walters can only admire the levels of significance that lie beneath Bennett's apparently simple dialogue. "Marjory is not facing up to things. She is keeping people at bay with her cleaning. She's washing everything away. She can't allow herself just to sit down and think. She speaks in this parochial language which conceals layers of God knows what. The most awful fears must be going on, but she keeps everything suppressed.
"Alan has this fascination with ordinary folk. He has a genius for ordinary language with layers of intricate, psychological stuff underneath. He's a very intelligent man, brought up in a working-class background, so he can look at ordinary life very creatively. Viewers take it in because they see elements of themselves in these characters. He has a way of getting the extraordinary out of the ordinary."
Which, as it happens, also stands as a pretty good summary of Walters' own attributes. In whatever part she has played - from the self-improving hairdresser in Educating Rita to the misunderstood mother in Jake's Progress - she has elevated the mundane to the mesmerising. In her hands, the girl next-door becomes someone exceptional.
Sitting in the splendid surroundings of the tea-room at the Grand Hotel in Brighton, the actress says she is attracted to playing "ordinary women, because that's what I was surrounded by as a child, that's my family. If you are fascinated by life, you drink in these people because somewhere in them is an answer to your own questions. It sounds pretentious, but any kind of art involves self-expression. I don't mean I'm an artist," she adds hastily. "A piss-artist, maybe."
Walters has a deserved reputation for comedy - her collaborations with Victoria Wood over the years have produced many classic humorous roles such as the hopeless cleaner, Mrs Overall, in the "Acorn Antiques" spoof- soap sketches, and the snooty actress in Pat and Margaret. Another one is promised in Wood's fist sitcom, dinnerladies, to be broadcast on BBC1 next month.
"It's a situation comedy, but it's a funny one - which is unusual," Walters explains. "It's set in a works canteen, and I play Victoria's mother. I had her when I was 13. Now I live in a caravan on the forecourt of a petrol station and it's an absolute tip. I'm refined, but I look like a wino. I only ever appear when there's trouble in my life. In one episode, I come in handcuffed to a policeman, and all I can say to my daughter is: `If you look in the caravan on the chemical toilet, you'll find half a shepherd's pie under a cardigan. I don't think the mince will go another day.' That sums up the character."
Some of Walters' most memorable performances, however, have actually been in more serious roles - think of the downtrodden wife in Boys from Black Stuff or the woman with ME in Wide-Eyed and Legless. Why is she so drawn to sad characters? "The things you want to crack are disturbing. That's what fascinates us. We don't want to analyse happy things because they might go away."
In the coming months we are going to be treated to something of a Waltersfest. She is playing a Northern Irish housewife peace-campaigner in the feature film, Titanic Town, Mrs Mann in Alan Bleasdale's version of Oliver Twist, and the Fairy Godmother in Jack and the Beanstalk, adapted by Simon Nye for ITV.
For all her successes as one of our finest character actresses, however, Walters has never been tempted to hawk her wares around Hollywood. "I can't think of anything worse than that sort of existence," she grimaces. "I would have to have had at least two face-lifts by now, and they wouldn't know what to do with me. I'm not saying I wouldn't go if Jack Nicholson offered me a starring role opposite him. But he hasn't rung once. The fool."
`The Outside Dog', this week's `Talking Heads 2', is on Tuesday, BBC2 at 9.50pm. The video, CD, cassette and book of the series are released through BBC Worldwide. `dinnerladies' starts next month on BBC1