Dettori took the 11-year-old to the front from the start of the Royal Bank of Scotland Handicap but appeared to be easy on his mount after being headed by the winner over a furlong from the finish.
After Cape Pigeon had finished third, beaten a length and a short-head, the stewards called upon Dettori to explain his actions but accepted his account that the gelding had had no more to give in the closing stages.
Gadsden, however, is far from satisfied and has threatened to bring to an end his activities as an owner. Cape Pigeon's trainer Gerald Cottrell said: "Having looked at the film, I think Mr Gadsden has a point. I think he gave the horse a tender ride over the last two furlongs - he didn't look hard pushed to me.
"We all have some funny ideas and can look at things through rose-tinted spectacles but he didn't seem to be making much effort. To put it mildly, he gave it a tender ride, and you wouldn't know the old horse has had a race. The owner is most disgruntled and upset, and you can see his point."
However Dettori, who himself returned from injury last Friday, rejected Gadsden's comments, saying: "I explained it to the stewards and they accepted my explanation, so he had better read the report. If I did anything wrong, I went too fast throughout the first part of the race."
The incident is not the first time that a "dream comeback" has been marred by controversy. Last October the Jockey Club looked into the victory of Jibereen - marking the return from serious injury of Declan Murphy - in a Flat versus jump jockeys' challenge at Chepstow.
Murphy was allowed to dictate the pace from the start of the seven-furlong race and was never challenged, landing some substantial bets in the process.
Having investigated the matter, the Club decided that no breach of the rules had been committed and took no further action. And yesterday its press officer John Maxse ruled out further scrutiny of the Windsor race by the disciplinary committee.