The Vanguard class are the Royal Navy's current nuclear ballistic missile submarines (Ship Submersible Ballistic Nuclear or SSBN), each armed with up to 16 Trident II Submarine-launched ballistic missiles (SLBMs). The class was introduced in 1994 as part of the UK government's Trident nuclear weapons programme.
The class includes four boats: Vanguard, Victorious, Vigilant, and Vengeance, all built at Barrow-in-Furness by Vickers Shipbuilding and Engineering Ltd between 1986 and 1999.
All four boats are based at HM Naval Base Clyde (HMS Neptune), 40 km (25 miles) west of Glasgow, Scotland. Since the decommissioning of all WE.177 free-fall nuclear bombs in 1998, and the removal of all nuclear weapons from the British Army, the Royal Air Force, and all surface ships of the Royal Navy, the Vanguard submarines' Trident SLBM system is the sole holder of the United Kingdom's nuclear weapons.