John Gosden has been fined £500 after a groom at his yard was found to have been the cause of Franconia's positive test for Ketamine last June.
Gosden accepted the disqualification of Franconia, although added his yard's zero-tolerance policy towards drugs and alcohol abuse meant he had taken all the steps to prevent any incident like this from taking place.
Both the British Horseracing Authority (BHA) and Gosden confirmed the source of the positive test was a groom, described by the trainer as being "vulnerable", who once the investigation had got under way, admitted to Gosden he was a recreational user of the drug on his weekends off work.
The groom added he believed he had caused the contamination by storing the drug in his wallet, which contained traces of the drug.
Further tests confirmed the low levels in the sample could not been caused by direct administration to the horse. Ketamine is used in veterinary practice as a tranquiliser, but has also become well-known as an illegal high which can be swallowed, snorted or injected.
"I think it's a nice place to work and overall we have a happy yard," Gosden said. "We take cleanliness very seriously. There are signs everywhere. We expect people to take pride in themselves.
"We have a zero-tolerance policy towards drugs and alcohol use, but in this case, one of my employees admitted to me that he was a user but only when not at work. He tried to cover it up, but he didn't manage to.
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"It took time, but he came to see me, he broke down in front of me and he was honest with me. I didn't think it was the right thing to fire him and he still works for me.
"It is my job to try and support my staff and now this is over, I will try to help him understand the seriousness of what he has done."
"Nobody is suggesting that you administered this drug or had any knowledge that it was being administered," responded BHA Disciplinary Panel chairman Philip Curl.
"The BHA are not suggesting that it is within your gift to completely stop your staff members from using drugs, but the BHA are saying that it is within your powers to advise your staff that they can cause a positive test from contamination and the question is whether sufficient steps were taken here."
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The panel ultimately concluded Gosden had "not proved on balance of probabilities that he had used all precautions to prevent a breach of the rule from happening".
"We wish to acknowledge the co-operation he gave the BHA in getting to the bottom of this matter and in supporting the staff member," said Curl.
"In the circumstances, we feel the penalty should take an unusual course and move outside of the normal guidelines and we therefore have lowered the fine to £500."