The Horseracing Regulatory Authority is holding an inquiry after reviewing TV footage of the incident at the Stratford races Sunday.

“I would just like to say to the public that I’m very sorry they had to see such a thing,” O’Neill said in a statement. “I’ve never done it before and it will never happen again.”

TV replays showed the horse, City Affair, being unruly in the parade ring, ultimately throwing O’Neill. The jockey got to his feet and grabbed the reins, before lowering the butt of his helmet into the horse’s nose.

“When I got to the start he headed straight for a car with me, stopped five feet from the car, whipped round and dropped me,” O’Neill said. “I landed on my feet but a bit awkwardly for my knee.

“I was a little bit angry then but I’ve never done anything like this before and I’m glad to say the horse is OK.”