The latest HMS Warspite was the third of Britain's nuclear-powered submarines, and the second of the Valiant class. After entering service in 1967 she collided with a Soviet submarine the following year. A mechanical failure associated with the submarine's nuclear reactor in 1991 led to the boat being laid up at HMNB Devonport where she awaits disposal.

The Valiant class were a class of nuclear-powered fleet submarines in service with the Royal Navy from the mid-1960s until 1994. They were the first fully British nuclear fleet submarine; the earlier HMS Dreadnought used an American nuclear reactor. There were only two boats in the class, the first, Valiant commissioned in 1966 three years after Dreadnought, and Warspite the following year. Both were built by Vickers at Barrow-in-Furness.