Irish raider Mr Boss Man was one of six winning favourites at Wolverhampton in the 32RedSport.com Handicap as one punter picked up over £245,000 for a total outlay of just £30.
The online William Hill customer, a 34-year-old from the Southampton area, backed every winner on the seven-race card, with his bet consisting of a £10 each-way seven-fold and a further £10 win seven-fold.
He placed his bets at 10pm on Tuesday night, taking a number of early prices.
Trained by Ado McGuinness, the eight-year-old Mr Boss Man was having his second trip to Britain in the space of a week after winning over a mile and three-quarters previously.
Stepped up to two miles and with a 6lb penalty, he just held on from Pass The Time under Pat Cosgrave as the 7-4 favourite.
"The two miles might just stretch him a bit on the Flat," said McGuinness.
"I think it was more to do with the fact that Pat got shuffled a bit further back than he ideally wanted. That meant going out on the second circuit he had to set him alight a bit to pass a few.
"Probably a mile and three-quarters is his perfect trip, though. We'll probably look at going back to Wolverhampton again, but we'll freshen him up first, that was his second time on the boat within seven days.
"He'd been consistent in Ireland, he was just running against well-handicapped horses. He started out running in some good bumpers and novice hurdles and we'll definitely look at going back over hurdles, he's still a novice until April.
"My main concern today was he wouldn't be fresh enough, but we just got away with it. He'll have a little break now."
Stuart Williams celebrated a double with Oakley Girl (9-4 favourite) and Ohsosecret (9-4 favourite).
Oisin Murphy was on the former in the EBF 32Red.com Fillies' Handicap, with Saleem Golam on the latter in the Download The New Unibet Racing App Handicap.
Richard Hughes and Shane Kelly have struck up a good partnership, and Bank Of Gibraltar justified 6-5 favouritism in the Ladbrokes Median Auction Maiden Stakes.
Clive Cox's Perfect Cracker (7-2 favourite) was another winning jolly in the coral.co.uk Handicap, with Brian Ellison's Whitecliff Park getting punters off to a flyer in the £10 Free At 32Red.com Apprentice Handicap at evens.
The only race not won by the market leader was the 32Red Casino Handicap, which went to James Unett's Artful Mind (9-2), ridden by Graham Lee.