Orange prize and a TV film puts Tremain well on the Road

The London writer, 64, secured the deal with the BBC just 24 hours before walking away with the biggest literary prize of her much-lauded career.

The novel is the story of Lev, an economic migrant from an unspecified eastern European country and his encounters with a London that is wasteful, obese and expensive.

It was hailed as "a powerfully imagined story and a wonderful feat of emotional empathy told with great warmth and humour" by broadcaster Kirsty Lang who chaired the Orange Prize judges.

Tremain afterwards revealed it is now to be made into a 90-minute one-off drama. "That's good," she said at the ceremony at the Southbank centre - where a memorable scene in her story is set.

But while her book made her hero's origins deliberately vague as an Everyman example of the immigrant experience, TV producers had already identified the need to "make specific a non-specific country".

It would be probably filmed "wherever it is cheapest," she admitted.

Tremain, who splits her life between London and Norfolk where she talked to immigrant fruit pickers, said the issue had hotted up since she wrote the book.The story had become politicised as a consequence. It would be "wonderful" if the book had a legacy of greater understanding, she said, but feared that was too ambitious a hope for a work of fiction.

"What needs to happen immediately is a tolerance of people coming here in search of a better life," she said. Few of them wanted to become British, unlike emigrants to America who had traditionally embraced the American dream.

"Our economy is, I think, on a downward spiral. There's no doubt that the economies of Poland, Hungary, Estonia, eastern Europe, are rising. People come here for a while to learn skills and the language and then they take the road home - and that might be to our loss."

Tremain said she had worked on her loser's smile. "Winning feels wonderful but it feels unexpected to me," she said.

The Orange Prize had in its 13 years earned a reputation for often honouring writers near the beginning of their careers. She had believed debut novelist Sadie Jones would win.

She defended the award against the criticism of many men - and some women. In her acceptance speech, she said: "Come on you guys, stop grumbling." This year Al (Alison) Kennedy had won the Costa, Anne Enright took the Man Booker and Doris Lessing was awarded the Nobel Prize for Literature. "I think there's a lot [for women] to celebrate," she said.

"All prizes exclude somebody," she said later. Attempts to make Americans eligible for the Booker had been defeated. "Are we so afraid of the strength of American writing - which has been undoubtedly awesome over the last 20 years?"

Tremain, who has one daughter, was married twice before falling in love with biographer Richard Holmes 16 years ago. Her first novel, Sadler's Birthday, was published in 1976 and she has written another nine including Restoration, which was filmed, and Music And Silence which won the Whitbread novel award.

The other shortlisted authors were Nancy Huston for Fault Lines, Sadie Jones for The Outcast, Charlotte Mendelson for When We Were Bad, Heather O'Neill for Lullabies For Little Criminals and Patricia Wood with Lottery. Joanna Kavenna, of Oxford, won a separate £10,000 Orange prize for new writers with her novel Inglorious.