It is not yet known whether King Charles III and Queen Camilla will attend to watch any of the horses they own.
Desert Hero gave the King his first winner at Royal Ascot with victory in the King George V Stakes last year, and is entered for the Hardwicke Stakes on Saturday.
Jockey Frankie Dettori will be back at the meeting, but not riding this time as he promotes a restaurant hospitality venture. He competed for the last time in Britain at Ascot in October before switching to the United States.
His absence gives Ryan Moore, O’Brien’s stable jockey, the chance to become the most successful current rider at the meeting – he is two behind Dettori’s mark of 81 victories.
It is also a big week for James Doyle, the first rider for Wathnan Racing, who have been on a spending spree before Ascot, snapping up the likes of Haatem, Shartash and Space Legend.
Wathnan – owned by Sheikh Tamim, the emir of Qatar – were successful with Gold Cup winner Courage Mon Ami and Queen’s Vase victor Gregory last year.