During the course of the six-hour operation, a metal plate and three screws were inserted into the damaged leg. He would never race again, but his life had been saved.
If Bonfire is to emulate his illustrious predecessor, he will have to get past a strong field including Aiden O'Brien's unbeaten colt Camelot, who goes into the Derby having already captured the Guineas. O'Brien's second and third strings, Astrology and Imperial Monarch, have both impressed on recent outings.
In any other year, Bonfire would probably be considered the favorite to land England's premier Classic, but Camelot holds that position with the British bookmakers.
Bonfire will be partnered in the Derby, as usual, by Jimmy Fortune, who will be hoping for better luck in running than their last outing at Group 1 level, when he finished third behind French Fifteen.
Fortune is adept at managing Bonfire's quirks but he'll need all his experience to cope with the famously fast Epsom course (the track rises 150 feet in the first half-mile, leveling out before a downhill stretch round Tattenham Corner).
"My father managed to win the Derby with a great horse, who was one of the most famous horses of the last century," says Balding. "It would be lovely to do it again."
The stone masons of Kingsclere had better be prepared to work overtime after Derby Day, because there might just be a yard with Bonfire's name on it.