As the Flat racing season got under way yesterday, Britain's oldest horse race took place 40 miles away. Sadly, it ended with the winner's untimely death

For the majority of the racing world, yesterday marked the start of the Flat season, traditionally launched with the Lincoln meeting at Doncaster. To a small section of the equine community, however, gathered 40 miles away on a hilltop in the Yorkshire wolds, it was Derby day.

It was not an occasion likely to have been much discussed in Epsom, even though the Kiplingcotes Derby claims to have stolen the march historically on the midsummer Classic by more than 250 years. A first prize of pounds 50 falls some way short of the riches on offer on the Downs in June, yet competition is no less intense. Sadly, yesterday's winning horse paid the ultimate price, collapsing from a heart attack a few strides past the winning post.

It would have been a glorious finish, but for its tragic aftermath with Sunny, a nine-year-old mare, finishing a length ahead of Memorable before collapsing under his rider Sheila Ashby. Sunny, again ridden by Ashby, won the race last year. "The race went so easily," Ashby, who runs a trekking centre near Thirsk, said, tearfully. "But her heart has just given out."

Sunny's death completely overshadowed Stephen Crawford's remarkable achievement in coming second on Memorable. The 41-year-old former accountant, whose home at Enthorpe railway station adjoins the course, had not ridden any horse before he bought the six-year-old gelding for pounds 1,000 in January.

He was raising money for Kingston General hospital in Hull, where his wife has been treated for skin cancer. Lyz Turner, news editor of the Holderness Gazette, was third on five-year-old Indy.

Sunny's death also nullified Ken Holmes' indignation. Holmes, a horse dentist from Selby, found his attempt to repeat his 1995 success on Tulum foiled first by a broken saddle and then by what he considered an illegal start. Holmes, who has ridden in the Kiplingcotes since 1982, has a record eight wins but makes no apology for his competitiveness. "It is a real test for man and beast," he said. "I don't mind being beat fair and square but what happened today rankles a bit."

The race is run over a gruelling four-and-a-half miles above Market Weighton on the third Thursday of March. It is said to have been taking place since 1519. This, the organisers say, makes it the oldest horse race in Britain, although the evidence is largely anecdotal.

Like the Epsom contest, which started in 1779, it was instigated at the fancy of nobility, who wanted to measure how well their horses had wintered. Eventually, 49 of them subscribed. Guy Stevenson, one of the present-day trustees, has a yellowing document which shows a pounds 30 donation from the Earl of Burlington, along with contributions from others ranging from pounds 5 to pounds 20, adding up to pounds 365. It formed an investment handed down through generations of trustees to provide the annual prize.

Nobility are thin on the ground these days, although Lord Manton was, until recently, a trustee. The race is open to allcomers, the only stipulation being that they turn up before 11 o'clock on the morning of the race to weigh in. A set of coal merchant's scales is provided. Each rider pays pounds 4.25 to take part and none must weigh more than 10 stone.

"People participate because it is a local tradition nowadays," said Sue Hillaby, the clerk of the course, who presented a ruddily rural face above a sensible country coat, only to reveal herself as a bank cashier from Hull. "This is just a one-day-a-year thing for me, but the clerk's job has been in my family for four generations and I like to maintain the tradition."

Hillaby sees that no one slips in under weight before reading the rules of conduct to the riders and despatching them on the half-hour walk to the start. Spectators pay nothing to watch, although there are no facilities.

Yesterday's turnout was conservatively estimated at 200, most of whom stood in groups along the former Roman road off the A163 that forms the finishing straight, with no apparent regard for safety. There were no barriers. Advice passed by word of mouth was that should three or more runners be upsides when they appear in the distance, then diving through the nearest hedge should be considered.