A racehorse owned by the Queen and trained in Newmarket has been disqualified from her second place in this year’s Gold Cup at Royal Ascot following a British Horseracing Authority disciplinary panel hearing in London.

A post-race sample containing morphine had been produced by Estimate, although trainer Sir Michael Stoute did not face a penalty as the source of the positive test had been found to be contaminated feed, with the BHA satisfied all reasonable precautions had been taken to avoid any breach of the rules.

Despite that, the Rules of Racing state that horses producing a positive sample for a prohibited substance should be disqualified from relevant races.

Estimate won the Ascot Gold Cup in 2013 for the Queen in a victory that was hugely popular and marked the first win in the feature race at the meeting for a reigning British monarch.

Stoute’s Russian Realm was ninth in the Buckingham Palace Stakes at the Royal fixture this year and was another to be disqualified.

The BHA tweeted: “The horses have been disqualified from the races in question. No financial penalty has been imposed upon the trainer.”

Four other trainers – Barry Hills, Charlie Hills, Gay Kelleway and Tony Carroll – also faced having horses disqualified at today’s hearing, all in the same circumstances as Stoute.