REGRETS? Dick Francis has a few. For example, he mourns the five years during the second world war which he spent in a Spitfire when he would rather have been riding horses. Nothing, however, can compare with not winning the Grand National on Devon Loch, the Queen Mother’s horse, half a century ago. Over mid-morning coffee in the lounge of the Goring Hotel, close by London’s Victoria Station, Francis recalls that fateful day in painful detail. Devon Loch was one of 29 contenders for racing’s most coveted prize. Though only the fourth favourite, he took the awesome fences as if jet-propelled. As one horse after another fell by the wayside, Devon Loch eased into the lead and by the time he came to the last fence the result looked a foregone conclusion. Over it he went as if it were a matchstick.

Now all he had to do was canter to the line and savour the glorious moment. Then, with just yards to go, the unthinkable happened: Devon Loch collapsed. One minute he was moving smoothly along, the next he was lying on the sodden turf, legs splayed, slithering in the Aintree mud. Against the odds Francis remained on board. He was so far ahead, he thought that if he could coax Devon Loch to his feet he could still win and enter the annals of racing history as a jockey who had won the National.

But it was not to be. Devon Loch’s moment, along with the muscles in his hindquarters, had gone. As other horses rushed by, their jockeys scarcely able to believe their luck, Francis walked away in disgust. “As I said in my autobiography,” he says, “an ambulance came by and the driver said, ‘Jump in the back!’ I was never more pleased to get away from all the people who were rushing towards me.”

What happened? “I’ve thought about it time and time again,” he says, still unable to provide an answer which will satisfy anyone, let alone himself. “I remember jumping the last fence and I could hear the crescendo of cheering building up in the stands. There were 500,000 people there that day. They were all cheering for the Queen Mother. She was there and the Queen was there and Princess Margaret was there. I never thought about it at the time but I heard them cheering and I just rode to the finish. I was winning easily. I didn’t have to pick up my stick or anything like that. I’ve looked at the newsreel time and again and as the horse approaches the water jump – which this time round he didn’t need to cross – you can see him prick up his ears and gallop past it. As it pricked up its ears – Christ! – his hindquarters refused to act and down he went on to his belly. How I didn’t fall off him I don’t know.”

Felix Francis, the younger of Francis’s two sons and now his manager and minder, adds: “I’ve seen it so often I just wish he’d win once.” But what of the Queen Mother? What was her reaction? She alone retained her composure. “How did it happen?” she asked. “I don’t know,” replied Francis. She shrugged. “Well, that’s racing, I suppose.”

Over the decades Francis has learned to be as philosophical. In compensation, his wife Mary once said that had he won the Grand National there would have been no bestselling autobiography and no thrillers. This is undoubtedly true. The British love nothing better than a loser, especially one like Francis who accepts defeat with such good humour and dignity. I’d read somewhere that after the debacle of Devon Loch he was suicidal. “I might have looked it,” he smiles, “but I wasn’t.”

Francis was 35 when the National slipped out of his grasp. The intervening 50 years have been spent carving out a career as a writer, in the course of which he has written 38 novels, a collection of short stories and two volumes of autobiography. Now a dapper 85-year-old, and after a five-year hiatus, “the master”, as his publisher insists on calling him much to his embarrassment, “is back”. His new novel is called Under Orders and – as his fans demand – it is set in the murky milieu of racing, where horses are nobbled, races fixed and owners, jockeys and gamblers are at each others’ throats.

As ever, Francis introduces a white knight to restore order, here employing for the fourth time “super-sleuth” Sid Halley who like himself is a former jockey. Unlike Francis, however, Halley is one-handed. “I myself have two good hands,” concedes the author, “but Sid Halley definitely has a bit of Dick Francis in him. At least, he is like I would like to have been. I hope [my protagonists] are humble and self-reliant, but above all I believe they possess courage and a sense of right and wrong. They are able to withstand great pressure both from mental torment and physical pain, and they are strong, decent and chivalrous; but they are ‘ordinary’ men, not super-human James Bond types.”

One suspects that as well as characteristics, Halley and Francis share many of the same likes and dislikes, among the former being schoolboy food – shepherd’s pie, casseroles, scrambled eggs – and women a head taller than them. Apopros the latter, his beloved wife, Mary, to whom he was married for 53 years, collapsed and died in his arms after an asthma attack in August 2000. Francis was utterly devastated. Throughout all their years together they estimated they’d only had four major rows, most of them early in their marriage. One was when he spanked her on the bottom while she was cleaning the grate. In response, she threatened him with a poker.

It was Mary, he says, who encouraged him to write when his days as a jockey came to an end. In his authorised biography of Francis, the journalist Graham Lord made the case for Mary as the chief author of the books. Francis, wrote Lord, “always wanted his wife Mary’s name to appear as co-author on the cover of the Dick Francis thrillers … but she would never allow it”. In contrast to her husband, who left school at 15, Mary was well-educated, with a degree in English and French, well-read and had worked in publishing. On the face of it, it seemed a no-brainer. Indeed, Francis thanked her in The Sport Of Queens, his first volume of autobiography and his debut as a writer, “for more than she will allow me to say”.

Mary, says Francis, told him to write it as if he were writing a letter to a favourite uncle. It was priceless advice. He then wrote The Sport Of Queens and she was “the first to read it and put the English right. I was rather inclined to use the split infinitive.” When he started writing novels, in order to pay his sons’ school fees, Mary immersed herself in research. “She was brilliant at the research,” he gallantly acknowledges, “and had the uncanny knack of asking the right questions to get the answers we needed. She learned all sorts of new skills in the pursuit of knowledge for the stories; she became a pilot for Flying Finish and Rat Race; she took up photo graphy for Reflex and painting for In The Frame. We would discuss the plot every night and she would read through my pages and polish the prose.”

But with Mary’s death the team effort was no more. In any case, they had agreed that they were ready to retire to their home in Grand Cayman, a time-warp British colony in the Caribbean where cars drive on the left and tax is nonexistent. Suddenly, Francis faced a lonely old age.

“They say that time cures,” he says, “and it does in so far that the raw pain of grief slowly diminishes, but time alone does not heal the hole that exists in the heart, the void that can only be filled by the presence of someone you love.”

That void, though, has been filled. Invited in April last year to speak at an event in Maryland, Virginia, he found himself dancing with a 60-year-old woman by the name of Dagmar Cosby. Bold as brass, he asked her if she’d like to visit him in the Caribbean, an offer she felt unable to refuse. Now, it would appear, they are an item. At the mention of her name his face lights up. She was the spur he needed to write again. He has even, says Felix, who in the absence of his mother was assigned the role of researcher, become adept at using e-mail in order to communicate with the new love in his life. Francis’s legion of fans owe Cosby a huge debt of gratitude.

However, whether there will be further Dick Francis thrillers remains to be seen. One certainly hopes so. Though thanks to Felix, Under Orders takes into account the manifold changes in the racing world and, in particular, the phenomenal rise in internet gambling, it is at heart a typical Francis thriller, keenly plotted, plainly written and decorously violent. Were it a television programme – which it should be – it could easily be shown before the watershed.

In that respect it is a reflection of the world in which Francis grew up, when manners still mattered, class counted and people could be divided into goodies and baddies. Whenever he is asked why he always writes about horses he says he doesn’t. He insists he writes books about people. “Horses may always be in there somewhere but it is the people who act out the story on the page … The horses and the racing world merely act as the canvas upon which the story is drawn. To say that Dick Francis novels are all about horses is like saying that Gone With The Wind is all about the American civil war.”

He is not trying to be disingenuous but he could no more leave horses out of his work than Updike could eschew sex. Though not actually born in a stable he was as near as dammit. His grandfather was an amateur jockey and his father was a successful horse dealer. He rode for the first time when he was three and was a professional jockey at the age of five. “My brother bet me sixpence I couldn’t ride a donkey over a jump.” His first professional ride was on a horse called Russian Hero which – irony of ironies – went on to win the Grand National in 1949 though not, alas, with Dick Francis on board. He was on the runner-up. Some things are just not meant to be.

Under Orders is published by Michael Joseph, £18.99