The four-year-old triggered a 33-1 upset when landing the Queen Anne Stakes at Royal Ascot in June.
The son of Delegator had no answer to the fearsome turn of foot exhibited by Alpha Centauri in the Prix Jacques le Marois at Deauville on his latest appearance, when he finished tenth and over 13 lengths adrift in Normandy.
With Queen Anne third Lightning Spear going on to win the Group One Sussex Stakes the Queen Anne may not be as weak a top-level race as first appeared but nevertheless the Oxfordshire handler has lowered her charge's sights for the Group Two assignment.
Accidental Agent faces no easy task as he must concede weight all round due to his Group One penalty but Johnson Houghton feels he is up to the task.
“Accidental Agent has got to carry a Group One penalty but I believe that he is still improving and I can’t see why that won’t negate the burden of having to give weight,” she said.
“He has only run below par once this year and that was when he was under the weather.”
“I think he went over to France for the Jacques Le Marois with some kind of bug on him, he was very quiet while he was over there. The travelling brought it out and he was very low for two weeks afterwards.”
“He has thrived since then and he has to run in the Joel as he is a gross horse and waiting another month for the Queen Elizabeth II Stakes would be too much.”
“I believe that a couple of the other runners have made the running in the past but if they don’t go a great pace, so be it, Accidental Agent did twice win over seven furlongs last autumn.”
“He seems in very good form but Mustashry looks useful and giving weight to him will be hard.”
Accidental Agent is no better than 6-1 for the contest, with the Sir Michael Stoute-trained Mustashry the market leader at 7-4, following his recent triumph at this level in the Park Stakes at Doncaster.
Stoute also saddles Regal Reality, while Roger Varian’s Zabeel Prince and Zonderland from Clive Cox’s yard complete the small but select field.
Group Two honours are also up for grabs in the Shadwell Rockfel Stakes.
Aidan O’Brien is represented by Just Wonderful, who bids to bounce back from a disappointing showing in the Moyglare Stud Stakes at the Curragh less than a fortnight ago.
The home team includes Varian’s hat-trick seeker Yourtimeisnow, Mark Johnston’s Albany Stakes winner Main Edition and Richard Hannon’s pair of Ajrar and Canton Queen.
Unforgetable Filly, trained by Hugo Palmer, heads nine runners in the Listed Muhaarar British EBF Rosemary Stakes which opens the seven-race card.
The Group Three Princess Royal Nayef Stakes features the Hughie Morrison-trained Star Rock and Stoute’s Sun Maiden, while Varian’s Barsanti and Brian Meehan’s Raheen House are among five runners in the Mukhadram Godolphin Stakes.