Frankie Dettori rode the winner of Goodwood’s only Derby trial on Friday as Private Secretary outstayed six rivals in the Cocked Hat Stakes but then confirmed that he will probably need a call to partner one of Aidan O’Brien’s extensive team of runners if he is to take a 24th ride in the Epsom Classic a week on Saturday.

John Gosden, Private Secretary’s trainer and who retains Dettori to ride, still has Humanitarian, a fluent winner at Salisbury this month, among the possible runners for the Derby. Dettori, though, said after Private’s Secretary’s success that even if Humanitarian lines up at Epsom, he will not be in the saddle. “No,” he said, “John’s told me that I can look elsewhere.”

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The obvious, perhaps only, place for Dettori to start looking is O’Brien’s Ballydoyle stable, which could have at least six runners in the Derby and currently houses the first three names in the betting in Sir Dragonet (3-1), Broome (4-1) and Anthony Van Dyck (5-1). Japan (11-1) is also still in line for a place in the Classic field, along with the relative outsiders Cape Of Good Hope, Norway and Mohawk.

The booking of Dettori, who rode Scorpion to win the St Leger for O’Brien in 2005 when he was still retained by the rival Godolphin operation, for any of the possible runners would excite plenty of interest from punters. A place in the saddle aboard one of the current “big three” from the yard, meanwhile, could easily see it set off as favourite at Epsom.

More clarity in the likely list of runners and riders can be expected on Monday, when both Sir Dragonet and Hughie Morrison’s Telecaster, the winner of last week’s Dante Stakes at York, could be added to field via a supplementary entry at a cost of £85,000 apiece.

Private Secretary, who had been touted as a possible Derby runner at the annual Breakfast with the Stars event at Epsom earlier in the week, will now head instead to the ‘Ascot Derby’, more formally known as the Group Two King Edward VII Stakes at next month’s Royal meeting.

“He loved the ground and he’s maturing,” Dettori said after coming from several lengths off the pace to win with something in hand.

“I had a bad draw so I had to sit last and I was further out of my ground than I wanted to be, but he showed a good turn of foot and won really well in the end.

“He will be a good King Edward VII horse in three weeks’ time, a mile-and-a-half will be ideal for him and I think he will be better on a track like Ascot.”

Private Secretary can be backed at around 6-1 for the King Edward VII and at 14-1 for the only Classic that he will be able to contest, the St Leger at Doncaster in September.

The style of Friday’s win suggested that the extended trip at Town Moor could well be within reach for Private Secretary but Thady Gosden, representing his father, has yet to be convinced.

“He is out of a nice staying family, but he is by [the miler] Kingman,” Gosden said, “so I think a mile-six will be a bit far, but hopefully he will stay the trip well at Ascot.”