British jockey William Carson has been banned for six months after testing positive for a metabolite of cocaine.

His suspension has been backdated to start from April 4 - eight days after the sample taken from him at Lingfield was found to contain the banned substance benzoylecgonine.

Carson, the 29-year-old grandson of five-time champion and multiple Classic winner Willie Carson, received confirmation of his punishment at a BHA disciplinary panel hearing on Thursday.

His ban runs through to October 4 and if he receives clearance from the British Horseracing Authority's medical team, he will able to resume his career next month.

Without a winner this year, Carson has not ridden since April 1. His biggest career success to date came in the 2008 Ayr Gold Cup aboard Regal Parade.

Willie Carson told the Racing Post his grandson had been suffering with depression but was "happier now than he's been for many a year".

"He's had depression and has got into the drink and cocaine after that. The best thing that happened to him was that he got caught," he said.

"He's been on a self-imposed ban from riding and he's now three times a week attending AA, and I believe he's even started going to church. We're told with his addictions that he's on the road to recovery, but with addiction you never know."

Carson also called for more frequent testing of jockeys.

"My feeling is there's a hell of a lot more involved in drugs and drink," he said.

"And that's in the whole of society not just jockeys. I would suggest to up the dope tests to once a week for everybody, or something like that.

"It would deter any young, aspiring jockeys who could go on to be very successful. That's what you need to stop this: a deterrent. They're taking it because they think they can get away with it."