IT is a dereliction of duty to chronicle the history of AP McCoy in trophies, races won and lost, or horses driven to the line or horses that drove him to distraction, with a detour at the local accident and emergency.

Worse, it is laziness and sloth should not be brought into the orbit of the most intense sun in the sporting galaxy.

The key to Tony McCoy lies beyond the small type of racing form, lies somewhere behind a pair of eyes in a gaunt face that does not flinch from a biting Scottish wind. McCoy was in Ayr yesterday, accompanied by his undoubted genius and his indefinable but enduring capacity to persevere against all odds, against the very top weight of history. His greatest triumph, in a lifetime of success, may be that he remains in essence a mystery.

The National Hunt jockey is painfully aware of the tangibles of life, particularly when they come up to hit him when he is travelling at 30mph on a thoroughbred that no longer finds him agreeable company.

But McCoy is about will and spirit. These traits defy anything other than the banal definition with the facility of a jackpot dodging the mug punter.

However, if one was to be obstinate and demand a history of McCoy in 100 objects then surely at No.1 would be the potato. This sultan of starch can be called upon to testify to the extraordinary appetite for winning that McCoy cannot sate.

In the millions of words unleashed upon the world in the aftermath of McCoy's declaration of retirement at the end of this National Hunt season, one sentence stood out like a Classic winner in a field of dray horses. It came from Chanelle, his wife, who stated simply: "I have not cooked a potato for him in 15 years. "

At 5ft 10ins, McCoy restricts his weight to 10 stone 4lbs, though he can add a few ounces when he goes on a steamed vegetable binge. He has been addressing his weight, politely but firmly, since 1992, when he rode his first winner.

The humble potato, that great chieftain of the tuber race, stands unwittingly as irrefutable evidence to McCoy's dedication. It has been his inconstant companion as he made a history that surely will never be altered.

McCoy has 19 consecutive championships, with a 20th awaiting, he has lifted all the great prizes: the Grand National, the Champion Hurdle, the Cheltenham Gold Cup, the King George, the Welsh and Scottish Grand Nationals.

As Kelly Martin, a bookmaker at Ayr yesterday, noted: "I have been taking bets for 20 years and I have never known a Champion National Hunt jockey who is not called AP McCoy."

Yet this domination of an era has not satisfied him. McCoy is the prime exhibit in the eternal display marked: Sporting Obsession.

His greatness is generally marked by the figures. He has won 4326 races, a laughably absurd number. These figures must be consumed with the relish afforded to a chip doused in vinegar: John Francome, the brilliant stylist, Peter Scudamore, the relentless winner, and Richard Dunwoody, who matched obsession with technique, won 1138, 1678 and 1699 races respectively.

Of course, McCoy, at 40, wanted more, specifically to ride 300 winners this season. One brief anecdote from the mouth of the great man does much to explain why he is calling time on the greatest sporting career in Britain, certainly in terms of supremacy and longevity.

The decision was reached when he accepted he could not ride that unprecedented 300. "I fell at Worcester one day and dislocated my collarbone, punctured my lung and broke a few ribs. I went back racing a few days later and thought I was fine."

Of course, you did, Tony, of course you did.

"But I managed to get another fall and broke the collarbone I dislocated. " He was forced to take a sabbatical of three weeks, making his target simply unattainable. "I struggled a lot mentally," he said.

This is such pure, distilled McCoy that it should count as four units for breathalyser purposes. The accumulated physical pain of a broken collarbone, smashed ribs and the pangs of hunger left him unmoved. The psychological hurt tormented him. "I thought that something I wanted to achieve was going to happen but then it was taken away," he said.

Brough Scott, whose brilliance with words is complemented by the substance of experience as National Hunt jockey, summed up the McCoy conundrum thus: "Do not doubt that while McCoy has been the nicest, best behaved lunatic on our planet, he has been a lunatic nonetheless."

This obsession has driven him into the winner's enclosure of life but it has also caused him and those he loves extraordinary anguish.

In the history of 100 objects, how about the fag that Chanelle smoked, prompting McCoy to throw her out of their home?

How about the washing machine he was found slumped against in despair after a day of losses?

How about the remote control he used to replay constantly the race he lost? It was one of six he had contested at Market Rasen that day. He had won the other five.

He bobbed out at Ayr yesterday on yet another leg of his farewell tour with some of these demons banished. His relationship with Chanelle is strong, perhaps forged by the shared past that had its troubles amid the huge financial and critical success.

He had three rides on a day when the punters were respectful rather than incontinently emotional. John Alexander, a pensioner from Kilmarnock, summed it up succinctly: "I have been punting for decades and he is the best I have seen over the jumps. I never seem to catch him, though."

He had three opportunities yesterday. The first saw the Antrim-born jockey finish second after his mere presence had made his mount, Top of the Glas, joint favourite. The third was in a NH flat race where he pushed Cornerman to an effort that was never likely to be rewarded by a payout for the punters.

But the second ride was a McCoy gem that illuminated a glowering Ayrshire day. He sensed on Yes Tom that he had to stretch the field to give his mount the best chance. The Irish horse stayed on to win, recalling McCoy times past with such as Martin Pipe. He was cheered by the crowd of 1300, more than 300 more than the organisers expected.

In the winner's enclosure he grinned like someone who has won for the first time. He arranged the owner and friends for the mandatory photograph. His sprint to the weighing room was stuttering, punctuated by acceded requests for autographs or even a handshake.

His life is raced at a gallop but he managed to dispense a measure of wisdom and experience to The Herald.

"My best win in Scotland would be the Scottish Grand National in 1997," he said. He seemed pleased with Sir Alex Ferguson's observation that he embodied humility.

"Humility?" he said. "It is very easy to stay humble in this sport. There is an ambulance following you around and that keeps your feet on the ground."

And, most crucially, when is going to have a potato? He laughed before pointing out one of his sponsors was Albert Bartlett, the potato suppliers.

"They have promised plenty of them for when I retire," he said, before disappearing into the weighing room.

The phenomenon lands at Kelso on Thursday. Witness him before he succumbs to that fish supper.