Ed Walker’s filly was fifth in the Commonwealth Cup at Royal Ascot and, down in grade for this Group Three against her own sex, she was sent off a 6-1 shot against 15 others.
She was allowed to dictate matters from the front under Paul Hanagan and although Shades Of Blue came out of the pack to challenge, Royal Intervention just edged it by a neck.
“She was already a winner at Listed level last year and she’s got some Group Two black type as well, so to win a Group Three with her is great,” said Walker.
“We’ll see where we go next. She’s obviously got the speed for six, but I’ve always felt she’ll stay seven.
“I’ll put her in the Prix Maurice de Gheest to try to get some Group One black type, but that is obviously a big step up and might be ambitious.
“The other option is to take her to America and see if she stays a bit further there,” he added.
At Newmarket, Mark Johnston’s Royal Ascot heroine Raffle Prize followed up with an impressive display in the Duchess of Cambridge Stakes.
With Frankie Dettori in the saddle, the 9-2 chance was sent straight to the front and gradually raised the tempo.
Daahyeh did her best to close the gap, but Raffle Prize was not for catching and was ultimately well on top as she passed the post a length and three-quarters to the good.
Johnston said: “Frankie said go for the Lowther or the Morny. That will be up to the owner, but she has won two Group Twos and I think we have got to have a shot at the Group One (Prix Morny) next.’’