Sam Thomas has been banned from riding for 17 days after riding the wrong course during a race in Norfolk.
The Gold Cup winner was leading The Light Dragoons Handicap Chase on the favourite Oumeyade when he pulled the horse up with a circuit still to go.
The stewards handed down a 14-day ban for taking the wrong course and a further three days for careless riding.
Thomas went on to win the next race to beat AP McCoy to the title of 2008's most successful jockey at Fakenham.
Thomas's finest moment came in March 2008 when he rode Denman to glory in the Cheltenham Gold Cup.
He is the second jockey this year to take the wrong course at Fakenham.
"He's a plonker, he got it wrong, it's as simple as that"
Denis O'Regan also picked up a two week ban in January when he rode a finish too soon.
Course commentator Derek Thomspon told BBC Radio Norfolk that he had a lot of sympathy for Thomas.
"He's a plonker, he got it wrong it's as simple as that.
"I went in to see him afterwards, I put my arm around him and said 'go out there and ride the next winner' which is what he's done."
Although he defended the jockey, Thompson said the jockey would find the mistake difficult to live down.
Thompson added: "His mum's a headmistress, his dad's a headmaster, he's probably the brainiest jockey riding in Britain, so the fact that he couldn't count up to three was slightly worrying."
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