Gunner B was a "strong, deep-bodied"[1] chestnut horse with a narrow white blaze bred by Tom Barratt at his Harness Grove Stud in Worksop, Nottinghamshire.
[2] He was the best horse sired by the American stallion Royal Gunner, who won the Cornhusker Handicap in 1966 and finished second to Roman Brother and Buckpasser in successive runnings of the Woodward Stakes.
He was dropped back to a mile for the Cecil Frail Handicap at Haydock Park at the end of the month and recorded his first important victory, winning by eight lengths, ridden by Joe Mercer.
He then won a moderate event over a mile and a half at his local Beverley Racecourse and then carried a big weight to victory in the Andy Capp Handicap at Redcar in early July, after which he was offered at odds of 8/1 for the St Leger Stakes.
When Gunner B contested the Gordon Stakes, a recognised St Leger trial at Goodwood however, he ran poorly and finished last of the six runners.
On his first appearance for his new trainer, Gunner B started at odds of 7/2[5] for the Group Three Earl of Sefton Stakes at Newmarket in April and won from Uncle Pokey and Gairloch.
At Royal Ascot in June, Gunner B started the 4/5 favourite for his second attempt to win the Prince of Wales's Stakes and won "without difficulty"[6] from the Harry Wragg-trained gelding Fluellen and the Prix Messidor winner Malecite.
He got the better of a protracted struggle with Radetzky to take the lead entering the final furlong and held off a late challenge from Balmerino to win by three-quarters of a length.
Hawaiian Sound took the lead soon after the start and although Gunner B mounted a sustained challenge in the straight he was never able to reach the three-year-old and finished second, beaten one and a half lengths.
Gunner B's final race was the Champion Stakes at Newmarket in October, in which he started third favourite behind Hawaiian Sound and the French filly Dancing Maid.
He tracked Hawaiian Sound throughout the race, but was unable to quicken in the closing stages, finishing third of the ten runners behind Swiss Maid, beaten three lengths by the winner.
The stud's owner, Peter Hockenhull said "He put us on the map – he's practically built this place ... a Gunner B would always win a race somewhere, somehow" and added "He had the vet out just twice in 13 years.