The King and Queen will need the rub of the green to see another Royal Ascot winner on the penultimate day of the Berkshire meet.
Charles and Camilla will join thousands of racegoers for another afternoon of racing and have invited family and friends to watch the action on the turf.
Princess Beatrice and her husband Edoardo Mapelli Mozzi, and Lord Frederick Windsor and his wife, actress Sophie Winkleman, will be in the traditional carriage procession, along with Dame Darcey Bussell and JCB manufacturer Lord Bamford.
The King and Queen’s horse Hard to Resist will run in the Sandringham Stakes, but is a longshot with odds of 50-1, and is way adrift of the favourites.
The couple took on Queen Elizabeth II’s thoroughbreds and last year had their first Royal Ascot winner, when Desert Hero triumphed in the King George V Stakes.
Among the celebrities presenting the racing prizes will be actress Dame Maureen Lipman and the author Dame Jilly Cooper.