Tracey Corrigan, from Sawdon near Scarborough, was out in front throughout the Kiplingcotes Derby which is run over four-and-a-half miles of sometimes treacherous and rough terrain in the Yorkshire Wolds.
The bookies favourite, who has won the race on two other horses in 2014 and 2015, said she had tears in her eyes as she came past the finishing post and a lump in her throat: "I am absolutely delighted and relieved that the horse and I have come back in one piece. I was in the front from the off, I kept looking behind and saw nobody.
"It means so much - I only came to take part; I was going to stay at the back and be a number but I ended up doing quite well."
There was drama at the end of the race after Two Pancakes fell around three-quarters of a mile from the finish, galloping back up the course bridleless. But both he and his jockey Bryan Rawstron were uninjured.
In second place was Emma Sanderson, on Trumpstoo, who said: "It was a bit rough in places but my horse was 100 per cent and got me through the worst of it."
In two years time the race celebrates its 500th anniversary. Racing historian Chris Pitt, from Birmingham, who has been coming for the last 25 years, said: "I could have had Press accreditation for Cheltenham but I'd sooner be here. This for me is the essence of what racing started out as - and the fact it is nearly 500 years old. You couldn't wish to meet a nicer bunch of people, it is super sporting occasion and part of British heritage that we must look to preserve."
One of the quirks of the Kiplingcotes Derby is that some of the horses are ex-racehorses, but run under different names.
"Some riders keep their cards close to the chest than others which is part of the fun," he added. "You get everything from thoroughbred racehorses to hunters, eventers, show horses, ponies and even Clydesdales."
Nobody knows until the riders actually appear on the morning of the race who is actually going to take part - making it a tricky job for the race's only bookie Chris Johnson.
Mr Johnson said: "We have spies looking at the horses - some are obviously ex-racehorses, but some are in-between, not pit ponies exactly but don't have the natural ability of racehorses. There's a lot of guess-work."
His colleague Geoff Fielding summed up what is a unique day's racing: "It's like the Brigadoon of racing - because there is no one here, then everybody's here and at 1pm it will be deserted again and it will go back in the mists of time till next year."