Dettori, who was represented by John Gosden's wife, the barrister Rachel Hood, was deemed guilty of irresponsible riding at Pontefract nine days ago, his third offence of the season. Unless he lodges an appeal within 48 hours, his place on the Gosden-trained Tamure will go to Michael Kinane. An unsuccessful appeal would threaten his chances of riding at the Breeders' Cup.
His ban, which begins on Saturday, also rules him out of the Racing Post Trophy on 21 October, but he is free to partner Presenting in the Rothmans International at Toronto on Sunday because there is no Flat racing in Britain.
Gosden, resigned to losing Dettori, said: "I'm sure Michael Kinane will ride Tamure. The horse is in great form but I wouldn't want the ground to dry up too much. He breezed this morning and went very well."
McCarthy, aged 22 and based in Lambourn with the trainer Kevin McAuliffe, tested positive for cannabis and amphetamines. After the inquiry he said: "I accept that banned substances were found in my sample, however I have never knowingly taken amphetamines and cannot explain how I tested positive for them.
"I am determined that the offence will not be repeated. I am equally determined to pursue my career in racing and will work even harder than before to ensure I succeed. I would like to thank my boss, Kevin McAuliffe, for his support during a difficult and stressful time."
His solicitor, Andrew Chalk, said: "Sean realises he has been foolish and is determined that he will not make the same mistake."
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