HMS Vigilant (S30) is the **third Vanguard-class nuclear-powered ballistic missile submarine** (SSBN) of the Royal Navy, built by Vickers Shipbuilding at Barrow-in-Furness, launched in October 1995, and commissioned on 2 November 1996. Forming a vital component of Britain's continuous at-sea nuclear deterrent, it is capable of carrying up to 16 **Trident II D5** missiles with multiple warheads, alongside **Spearfish** torpedoes for self-defence, and operates with two alternating crews from its base at HMNB Clyde in Faslane, Scotland. Following a major mid-life refit completed in 2012 that included a new reactor core upgrade for life-of-hull operation without further refuelling, Vigilant has conducted extended patrols—including a notable 174-day deployment in 2024—amid fleet availability challenges and delays in the Dreadnought-class successor programme.
