A surprise winner of the Queen Anne at the Royal meeting in June, he has disappointed in two runs since in the Jacques le Marois at Deauville and the Joel Stakes at Newmarket.
While confirming the four-year-old stays in training next year, trainer Eve Johnson Houghton tweeted that he would miss the meeting at which he was fourth 12 months ago in the Balmoral Handicap.
She said: “Having met with a minor setback, we have made the decision not to run Accidental Agent again year. Although we are sad to miss the QEII @Ascot, we can’t wait for next year with him. #group1winner.”