Racing figures and authors have paid tribute to thriller writer Dick Francis, who has died aged 89.
Writer Frederick Forsyth praised Francis's "immensely prolific" output of "page-turners", and said authors were still "walking in his footsteps".
Former BBC commentator Sir Peter O'Sullevan said the best-selling writer was one of the "people's champions".
As well as being a best-selling author, Francis was also champion jockey in the 1950s and the Queen Mother's jockey.
He wrote more than 40 best-selling novels during his career, selling some 60 million books worldwide.
He first published his autobiography in 1957, and his first thriller, Dead Cert, followed five years later.
The Queen Mother was reputedly one of his most enthusiastic readers, and Buckingham Palace said the Queen would be saddened to learn of his death.
'Wicked sense of humour'
Sir Peter O'Sullevan called Francis "a very good mate" and said: "I particularly enjoyed reading his novels and found him a wonderfully efficient author."
Former jockey John Francome said: "He was a lovely person who always had a sparkle in his eye and he had a wicked sense of humour.
"I remember we used to laugh out loud about the old times."
Former champion jockey Terry Biddlecombe, husband of Best Mate's trainer Henrietta Knight, said: "He was a good guy and a lovely man and always a help to anyone.
"I knew him for many, many years and I read all his books and they were excellent."
Francis won numerous accolades for popular fiction in his genre, including Crime Writer's Association lifetime achievement award in 1996.
He was made a CBE in 2000 for services to literature.
Francis's most recent works, including Dead Heat and Silks, were co-authored by his son Felix.
Mr Francis said he was "devastated" at the loss of his father.
"We share in the joy that he brought to so many over such a long life," he said.
"It is an honour for me to be able to continue his remarkable legacy through the new novels."
During his racing career, Francis's most famous moment was when his horse, Devon Loch, fell when he was close to winning the 1956 Grand National.
In 2006, Francis said of the incident: "It was a terrible thing, but I look back on it now and I can say that if it hadn't happened I might never have written a book, and my books have certainly helped keep the wolf from the door."
After he retired from the saddle, Francis was the Sunday Express racing correspondent for 16 years.
He spent his final years in retirement in the Cayman Islands, and his family said he "died of old age".
A private funeral is due to be held in the Caribbean with a memorial service in London at a later stage.
The next novel co-written with Felix Francis is due to be published in the autumn.