Sam Twiston-Davies has apologised for the error that led to him being unseated on Hawkhurst within yards of certain victory at Southwell.
Favourite Hawkhurst was clear after the final jump when he jinked to the right and dumped Twiston-Davies out of the saddle.
Twiston-Davies, 23, tweeted: "Apologies to all with Hawkhurst. I can only say sorry. An error on my part."
Weststreet went on to win the Flames of Newark Novices' Hurdle.
Stewards inquired into the incident but after interviewing Twiston-Davies and viewing recordings of the race took no further action.