Trainer John Gosden will walk the Ascot track before deciding whether Golden Horn runs in the King George VI And Queen Elizabeth Stakes.

Heavy rain has already prompted the withdrawal of French horse Flintshire from the mid-summer showpiece on Saturday (Sunday AEST).

Unbeaten in five starts, Derby winner Golden Horn added the Eclipse Stakes against older horses to his record last time out.

Ascot clerk of the course, Chris Stickels, said an inch (25mm) had fallen at Ascot on Friday.

"It's the wettest Flat day I can remember," Stickels told Racing UK.

"I've spoken to John (Gosden) and he was pleased to hear we will move the rail on the round course overnight and that will provide fresh ground as the King George is the first race on the round course.

"John said he will walk the course and make a decision then, that's his plan at the moment."