Leicester's fairy tale saddles bookmakers

The bookmaking industry faces its biggest loss in Premier League history with Leicester City just a win from clinching a shock first title.

So unexpected was their title chase, major bookmaker William Hill says it quoted Leicester as 5000-1 outsiders at the start of the season.

Now the loss stands at about STG10 million ($A18.79 million), William Hill said in a statement on Tuesday.

A man from Guildford, England stands to earn the highest individual payout after wagering STG75 at 1500-1 just a few weeks into the campaign, it said.

He has not cashed out and so now stands to win STG112,500.

In total, William Hill face a final payout of a little over STG3 million if Leicester beat Manchester United at Old Trafford on Sunday.

"We stand to lose a small fortune if Leicester do what everybody must now be expecting them to do. 5000-1 is the biggest priced winner in betting history!" William Hill spokesman Joe Crilly said.