The unbeaten Without Parole confirmed he will be a match for all the milers this summer with victory in the  St James’s Palace Stakes at Royal Ascot.

The son of Frankel, trained by John Gosden and ridden by Frankie Dettori, was the 9/4 favourite and is owned and bred by John and Tanya Gunther, who bred American Triple Crown winner Justify.

Ryan Moore most of the running at a strong pace on the Aidan O’Brien-trained U S Navy Flag but Without Parole overhauled him a furlong out. He then responded well to Dettori’s urgings to fend off the late challenge of Gustav Klimt, also trained by O’Brien, to score by a half-length.

Gosden said: “US Navy Flag had gone, and Frankie said, ‘I had to go after him – I was frightened he had got three lengths, and in the end I went a bit soon’. Then of course with Aidan [trainer of both US Navy Flag and Gustav Klimt] there is another arrow at your back – there always is another arrow.

“But look, Without Parole is a grand horse. There were no hiding places in that race. It was proper, proper Group One pace. I think he is still on the up and still learning.

“He could stay at a mile or go up. He was green on the bend and Frankie was having to say, ‘come on old boy, come on old boy’. He’s so lazy at home. I’ve never seen a horse eat and sleep like it, which is a great, great thing in a racehorse. I think he will improve, he’ll get sharper and I think he will get a little further too.”

Gunther said: “It is a dream come true. In all the 20 years I have been coming to Royal Ascot, my dream was just to have a horse run at Royal Ascot. Then we start in a Group One and do it; I don’t know what to say.

“This does mean more [than breeding Triple Crown winner Justify] and always will. This was the most important and means everything to me.”

Wootton came from well off the pace to claim third, with Tip Two Win fourth. Roger Teal, trainer of the latter, said: “The race didn’t quite go to plan and we were further back than we wanted to be, and he had a lot of ground to make up. We were mindful of the stiffer mile here at Ascot and David [Probert] gave him a bit of cover to help him to settle, but they went a crazy early pace which did not help.”