Debut novelist Stef Penney, once an agoraphobic too terrified to travel, landed one of the top literary awards for a haunting novel about the Canadian wilderness she had never visited.

Penney, a screenwriter who now has her claustrophobic condition under control, landed the Costa Award for "The Tenderness of Wolves", which literary critics hailed as an astonishingly assured debut.

"Within 50 pages, I was completely in love with it," said comedy writer and director Armando Iannucci, who chaired the panel of judges that gave the prize to Penney's intriguing journey of imagination.

The 37-year-old British writer landed the coveted award in a close fought tussle with novelist William Boyd for his spy drama "Restless" and Brian Thompson for his quirky wartime biography "Keeping Mum", Iannucci said.

Penney, who conquered her agoraphobia after a two and a half year battle before going out to research the book in the British Library, revealed at the awards ceremony: "I was fascinated about Canada because I couldn't go there."

"It made me want to armchair travel," she said. "Something did eventually cure me. Whether it was part of that, I don't know, but perhaps it was. The more I researched the more fascinated I got," she said of the novel that takes place in a remote corner of 1860's Canada.

The Costa, formerly known as the Whitbread prize, was selected this year from a record 580 entries and is designed to award the most enjoyable read of the past year.

Level: A2