65-year-old Tremain, who lives in Norfolk, was the bookmakers' favourite and she beat five other writers for the 30,000-pound prize and a bronze statue, which is open only to women, at the Royal Festival Hall here last night.
The main character in her novel is Lev, an eastern European who travels to Britain to seek work following the death of his wife. He arrives with no money and little English, and the story charts his struggle to adapt to life in an alien land, first in London and then in rural Suffolk.
Kirst Lang, the broadcaster and chairman of the judging panel, described the book as "a powerfully imagined story and a wonderful feat of emotional empathy told with great warmth and humour".
Tremain, who was shortlisted for the prize in 2004, was appointed a CBE for services to literature last year. Born in London in 1943, Tremain published her first novel, "Sadler's Birthday" in 1976. She won Dylan Thomas Award for four short stories and the Whitbread Novel Award for "Music and Silence" in 1999.
