A racecourse judge may face an inquiry after naming a winner at Lingfield on Monday and then changing her mind.
Judge Jane Stickels initially declared 9-4 favourite Welsh Dragon as winner of the littlewoodspools Handicap by a short head over 14-1 shot Miss Dagger.
But after the weighed-in signal was given, she changed her decision and reversed the placings, forcing some bookmakers to pay out twice.
Bookmaker Barry Dennis has threatened to take legal action.
"I shall start by suing Stickels and if she won't pay, I shall sue Lingfield Park racecourse - then I shall go on to the Jockey Club," he said.
"Someone else has got to pay - the bookmakers have had enough of this."
Prize money will be distributed in accordance with the amended result and the matter is now set to come under the Jockey Club's internal procedures.
"A report will be sent in from the stewards and then there will be an internal procedure that we will follow to see if any action will be taken," said Jockey Club spokesman Paul Struthers.
"There will be an internal review much as in the same way anyone who works for any company with internal procedures.
"It would be totally inappropriate to comment on what they might be."