The BBC's Nick Higham: "Mary Francis has always admitted having a hand in the books"

A new unauthorised biography, Dick Francis: A Racing Life, suggests that Mary Francis wrote most of the former jockey's novels but shunned the limelight in favour of the pulling power of her husband's name.

Biographer Graham Lord, who has known the couple for 30 years, says Mr Francis's desire that his wife be credited as a co-author gives credence to the claims.

He also points to the fact that Mr Francis left school at 15, while his wife gained a degree in French and English before working for a publisher, as evidence that Mary is the real force behind the books.

Teamwork

But publishers for Mr Francis, 78, who was born in Lawrenny, south Wales, say while Mary has always helped with research, it is he who writes the bestsellers.

Shunning the limelight: Mary Francis

A spokeswoman for Michael Joseph said: "Dick and Mary have never made a secret of the fact that they work together on their books - they are very much a team.

"He has also made it clear that he would like Mary to have a co-author credit but while she helps with the research and discussing the books, it is Dick who writes them."

Mr Francis's 40 crime thrillers have helped make him one of the most successful post-war authors, selling more than 60m copies worldwide. He and his wife live on the Cayman Islands.

The 400-page biography recalls a conversation in 1980 between Mr Lord and Mary Francis about whether she wrote the books under her husband's name.

Brough Scott: "Dick writes bits and she writes bits"

Mr Lord claims she said: "That's an impossible question to answer. Yes, Dick would like me to have all the credit for them but believe me, it's much better for everyone, including the readers, to think that he writes them because they're taut, masculine books that might otherwise lose their credibility."

One man who knows the couple well - the broadcaster Brough Scott - told BBC Radio 5 Live the books were very much a team effort.

"They have always done these things together. They go and research them together and talk about the plots.

"Dick writes bits and she writes bits and they put it together and exactly who finally polishes up every comma to me is really irrelevant.