The eleventh HMS Vanguard of the Royal Navy is the lead boat of her class of Trident ballistic missile-armed submarines.

Vanguard was built at Barrow-in-Furness by Vickers Shipbuilding and Engineering Ltd, later BAE Systems Submarine Solutions, was launched on 4 March 1992, and commissioned on 14 August 1993 in the presence of Diana, Princess of Wales.

The United Kingdom Ministry of Defence initially would not comment on the incident, which was however confirmed on February 16 by First Sea Lord Sir Jonathon Band.

[12] In February 2023, the Royal Navy began investigating claims that broken bolts for the reactor chamber on Vanguard had insufficiently been repaired using glue, during her seven year refit.

Babcock is one of the United Kingdom's largest defence contractors, with contracts for the maintenance of both the Royal Navy's Astute-class and Vanguard-class submarine fleets.