Writing had been "a secret dream" even since the days of Mr Moles and The Pick- wick Papers. But, she says, it was an impossible dream. "Because it is impossible. I still don't feel that I've done it. I just read and read compulsively. I knew I was different. I noticed things when I was a child. I used to walk to school with a gang of kids and I would notice things and point them out and would see their bafflement. `Why is that interesting? What is she talking about?' "

In 1979, Colin persuaded her to enter a playwriting competition run by the Phoenix Theatre, Leicester, one of England's most innovative repertory theatres. Not only did she win, she was asked to become the Phoenix's writer-in-residence. Several plays followed. Then an actor friend asked if she had anything that he could use as an audition piece. She had. A monologue, a spoof diary of a 14 and three-quarter-year-old local boy called Nigel Mole, based not on her own sons but on herself. The actor loved it and showed it to BBC radio producer John Tydeman, who immediately commissioned a full-length radio play, which was broadcast on New Year's Day 1982, with Nigel's name changed to Adrian and his age dropped by a year. The next step, again championed by Tydeman, was the novelisation, in which Tydeman's genuine letters to Townsend's alter ego themselves played a part.

There was only one real moment of triumph, Townsend recalls, when she and Colin went shopping for a car. "It was always Colin's fantasy to have a Citroen, so we went to the showroom and did a test drive. We must have looked terrible. It was late afternoon and I had just come from the adventure playground and I was wearing this sheepskin coat that stank of bonfire, and Colin had come from the farm and stank of goose shit. And so the salesman must have thought, `Oh yeah'. When we came back he said, `Did you like it?' `Yes,' we said. 'We'll have it.' "And he said, `How are you paying?' And we said, `Oh, cash.' Then he said, `And when would you want it?' And we said, `Tomorrow.' And he said we couldn't get one for 11 weeks or something, and then only if we wanted it in orange. `No,' we said. `We want it in metallic grey, and tomorrow.' Otherwise we'd go somewhere else. It was an eight-seater of a kind of extended estate because by then we had four children. And we got it. And I remember watching his face, just waiting for that moment. I knew his face would change. `Oh, cash. Oh, please sit down. Perhaps I can get you some coffee.' "

She does the Uriah Heep-style voice, face and hands. "So that's the only moment of triumph," she pauses. "And revenge."

The bonfire at the adventure playground had been her idea. They had one every night, burning junk, rubbish. "We'd sit on these old three-piece suites, me and the lads, and we just talked. It was structured from my point of view, but they didn't know. It was the only light and heat we had, because we were working in a field before the building was built. We had no funding for the building; in fact, when the building was built, then everything went downhill, because then you change into a caretaker with bloody keys, going around locking things."

Sue Townsend still sees some of her "old boys" from the adventure playground days in her local prison, where she teaches and talks to writers' groups. "It's one of the ways you can get an education if you're working class: you go to prison. Some of those boys have got three degrees."

Like them, Sue Townsend hopes to up the literary stakes before too long and to write something more like the books that inspired her, specifically an English Madam Bovary, she says. For a moment I am convinced. Why not? As a writer she is more than up to it. Then she tells me the title she has in mind. "It's A Lump In The Bed," she says. "Because that's how a male acquaintance of mine referred to his wife, as in "Well, better go home to the lump in the bed." She hasn't actually started it yet, though she says she has been writing things down, exploring her. "Because she will spend most of her time in bed."

I can't wait.