William Hart was born in Kennington, London on 24 January 1909. He joined the Royal Navy as a Stoker Second Class on 25 January 1927 and signed on for a twelve-year engagement. On 12 August 1927 he was drafted to the battleship HMS RAMILLIES where he was advanced to Stoker First Class on 24 October 1927. He then joined the destroyer HMS TRINIDAD on 20 November 1929, followed by the cruiser HMS DIOMEDE and then the sloop HMS VERONICA. On 3 February 1931 HMS VERONICA was anchored in the Bay at Napier in New Zealand when a major earthquake took place causing severe damage to the town, the port facilities, and the surrounding area. The crew of VERONICA then provided support to the civil authorities for several weeks. William Hart served in HMS VERONICA until November 1931.

William Hart joined submarines at HMS DOLPHIN on 18 May 1932 and joined HMS H43 on 15 August 1932. He was seriously injured in a motorcycle accident on Thursday 15 December 1932 and died later the same day in the Sittingbourne Memorial Hospital. William Hart is buried in the Woodlands Cemetery in Gillingham, Kent in the Naval Section in Grave No. 857