Gallinule's dam, Moorhen (1873), was by the influential sire and Derby winner, Hermit.
Gallinule was a handsome chestnut colt with two hind stockings, a front sock with a strip that ran from his knee to merge with it, and a bit of white along his coronary band on his other foot.
Gallinule is also seen in the pedigrees of some top jumpers, a talent he probably passed on from both his grandsire, Sterling, and his long-running jumping dam, Moorhen.