Reigning Horse of the Year Show (HOYS) grand prix winner Robert Maguire will next week defend his title with a three-month riding ban looming ahead for him.

The 26-year-old Lancashire rider, who is now 14th on the BSJA riders ranking list, said he felt the ban, handed down by the FEI on 11 September, was “very harsh”.

The ban has been issued following a doping offence involving his top horse Two Mills Showtime, with whom he claimed last year’s Leading Show Jumper of the Year Grand Prix at HOYS in front of sell-out crowds. Later that month, on 29 October 2005, the horse tested positive to metabolites of acepromazine (ACP), a prohibited sedative, when tested at the CSI**** in Lyon, France.

“The day the horse was tested, he jumped really badly and I just couldn’t understand how the substance had got into his system — I know for sure I didn’t give him anything,” Robert told H&H.

The only silver lining for him is that the three-month ban does not come into effect until 30 days after 11 September, providing a window for an appeal and enabling him to compete at HOYS (4-8 October).

“Had the FEI decision come down a month earlier, it would have been tragic,” he said. “This case has dragged on for nearly a year and it does leave a bitter taste going into HOYS because I know I’m going to miss quite a few good shows and drop down the BSJA rankings.”

Robert, who did not contest the accuracy of the positive test result, said he had not come to a decision about a potential appeal. He was also fined 5,000 Swiss francs (£2,111) and ordered to pay 1,000 (£422) towards legal costs.

The FEI judicial committee panel found he did not deliberately try to influence his horse’s performance with the drug. But it underlined “gross negligence” on his behalf with regard to the organisation of his stable, especially involving the feeding procedure of horses.

In his written explanation, Robert said another horse at his stable was prescribed acepromazine, adding that the only possible explanation for the drug being present in Two Mills Showtime was that feed buckets may have been mixed up or not washed out properly.

The panel was told his horses were now given feed, mixed from a large trolley at individual stable doors.