The peak of his career came only in 1829 when, aged 60, he performed the remarkable feat of both riding and training the Derby winner.

[1] A year prior, he had placed a bet with a bookmaker named Crockford that he would win the race on a horse, The Exquisite, which he trained and planned to ride.

On exhumation, however, the horse's lower jaw was found to be missing, Forth having removed it earlier to protect his friend.

[2] The following year's Derby would be happier for Forth, recording a third win as a trainer with The Merry Monarch, ridden by Foster Bell.

He died on 4 February 1848 at Oxford Street in London, after a long illness, and was buried in St. Martin's Churchyard, Epsom.