Julie Walters learnt to drive, at 37, only after she fell in love. She met Grant Roffey, an AA man, who moved in after a whirlwind romance. Personal tuition behind the wheel was a fringe benefit. And, much to her surprise, it sparked another love affair — the thrill of driving. “I could not,” she recalls, “believe how much fun it could be.”

Walters passed her test first time and immediately invested in a smart new Mini, which she had customised to a convertible. “It looked like a Mini in a headscarf,” she says. “But it was a real traffic stopper. People would ask me in the street where I’d got it from.”

There is a convertible version of the new Mini, of course, but in those days it was a rarity. “I loved that car,” she says. “It was not an electronic roof, but it was wonderful. It was a real thrill to drive, with the wind in your hair, on an open road. I suddenly realised what I’d been missing.”

Today, Walters, 57, drives a Toyota RAV4, which she uses on the 17-acre organic farm that Roffey runs in the wilds of Sussex. “I know it’s not very green to have a four-wheel drive,” she says. “But we are on a farm. We are two miles from a road and it is reached by an unmade forestry track. I used to have a Golf, but every time I got out of the car after that last couple of miles the thing was covered in mud up to the roof.”

Walters has had her moments on the road. “I had a Peugeot 205 for a time, which I loved — and then a Peugeot 205 with a 1.9 engine, which was really fast. That was probably a bit scary for me, because the moment you put your foot down it really did move. It was like, ‘Phew, I enjoyed that . . . but maybe I should take it easier’.”

Walters has certainly not been taking it easy on screen. She’s racked up 60 movies, television series or TV dramas since she won an Oscar nomination as best actress for her lead role in the 1983 film Educating Rita. And she’s done the lot: everything from comedies with Victoria Wood, to sex scenes with the 27-year-old former EastEnders star Paul Nicholls in the BBC’s 2003 Canterbury Tales.

Even in the past year, she’s starred in the small-budget film Driving Lessons, played the murderess Mrs Holland in the TV film The Ruby in the Smoke and will appear this summer in the fourth Harry Potter film as Molly Weasley. She can currently be seen playing Jane Austen’s mother, Cassandra, in Becoming Jane, the film about the author.

“I have always liked variety,” Walters says, “and that’s what I have got. I had not read any Jane Austen since I was 11, when we read Northanger Abbey at school. It was dreadful. I thought, ‘I am not reading her again.’ You need to grow up a bit and be aware of human nature before reading books like that.

“Now I realise how funny Jane Austen was. It is also quite modern, with a humour which has lasted 200 years. And these great roles are still coming my way, thank goodness. With the nature of drama, all the meaty parts about conflict, love, having children and struggle are for younger actresses. But there are good parts for us older ones, too — probably more so than ever.”

Walters and Roffey have an 18-year-old daughter and she says her job allows her to keep in touch with the younger generation. “I love working with the young lot. Anne Hathaway [Jane Austen] is particularly mature and intelligent, and Rupert Grint, who plays my son in Harry Potter, is a sweet boy. So I’ve got nothing but good things to say about them.”

She has also managed to retain her natural down-to-earth personality in a business renowned for luvvies and prima donnas.

“I have my vain moments,” she insists. “The fitting for the dresses and corsets in Becoming Jane was one of them. I said, ‘Yes, you can pull it in more.’ Did I regret that! I could hardly breathe, it was so tight. After a while, the bones started poking out of the corset and I had bruises. You loosen it when you have lunch, but when you tighten it again afterwards, you can feel your cottage pie coming up to your chest. Never again!”

Perhaps part of her charm as an actress is that she delivers believable characters that ordinary people are able to identify with. She stripped for Calendar Girls, the 2003 film based on the Yorkshire Women’s Institute members who made money for cancer research from their nude calendar, and danced to teach the working-class hero in the surprise 2000 hit film Billy Elliot.

Despite many approaches to move to Hollywood, she’s always remained firmly planted in the English countryside. “I like being a visitor to Los Angeles, so I never take it seriously,” she says. “It must be so hard to be an actor there, unless you are massively and consistently successful. I did not want to live my life like that.”

Walters celebrates her 10th wedding anniversary in June. “I had always been against marriage,” she says. “My late mother always told me, ‘Don’t think you have to get married. A husband can be a millstone around your neck.’ It was probably some of the best advice I received until I met Grant.

“But we have now been together for 21 years. In the end, we went off to New York, filled out all the forms at city hall, walked to a wedding chapel in Little Italy, had a meal afterwards and then went on the Circle Line boat trip around Manhattan. It seemed to capture the mood.”

On her CD changer

Snow Patrol. I tend to focus on one CD at a time and their latest album, Eyes Open, is the one at the moment. The track Chasing Cars is my favourite