Life-long fan solves Sayers's last Wimsey mystery

It was perfectly clear from scribbled notes whodunnit. The only question was, just who had been murdered and how?

Linking arms with the fictional young newlyweds Lord Peter Wimsey and Harriet Vane, writer Jill Paton Walsh was confident she could crack the mystery.

And luckily the literary trustees of the detective fiction writer Dorothy L Sayers were confident too. Together with literary agent Bruce Hunter at David Higham Associates they asked Paton Walsh to complete Sayers's unfinished Wimsey novel from fragments and sketches, and their decision has already had commercial success.

The novel, Thrones, Dominations, to be published by Hodder and Stoughton early next year, has been sold to Japan and Denmark. "It is extremely unusual to sell abroad so far ahead," said Bruce Hunter, "and of course it will go to America too."

Dorothy L Sayers wrote a series of novels and short stories during the Thirties featuring Lord Peter Wimsey. Thrones, Dominations would have followed Busman's Honeymoon, the last novel to be published.

Ms Paton Walsh, whose self-published novel Knowledge of Angels was shortlisted for the Booker Prize three years ago, said: "There was a wonderful 'starter pack' for me. The mise en scene was very interesting.

"It is set in London's theatreland in 1936. Harriet and Lord Peter are just married and his very posh family are adjusting to their new daughter- in-law.

"There is also a scene, unusually for Sayers, where they watch a public event - the funeral of the dead king (George V) - and this sets up many of the themes."

Sayers fans will find no ruler line between Paton Walsh's work and the original text. After mysteriously discarding the novel 60 years ago the author left several sketchy versions of the same incidents, along with a rough plot diagram and the name of the culprit.

"I certainly hope there is no sharp dividing line between her work and mine. She had left what is now a little under a fifth of the final book and I rewrote some of the scenes, just as I am sure she would have done."

There was also an element of repaying a debt in Paton Walsh's detective labour of love. A life-long admirer of Sayers's books, she believes she would never have worked so hard to get into Oxford as a teenager if she had not been inspired by the image of the university painted by the Wimsey novel Gaudy Night.

"I got in very much against the odds really, from a school which had never got anyone to Oxford before," she recalls.

Her wide knowledge of the other stories was her biggest aid in the task, but Paton Walsh also lent heavily on copies of the Times from 1936. She scanned news stories and theatre announcements for period information.

"I used my Oxford English Dictionary CD-Rom extensively to check vocabulary. It gives you all the words that were being coined in 1936." When polishing the final draft she and her editors felt it was more important that the book felt right than that it was historically accurate.

"I do miss both of them," said Paton Walsh of her time with Harriet and Lord Peter: "I feel very privileged to have had their early married life in my hands."