Conceptual design and development of the highly complex second generation Ship Submersible Ballistic Nuclear (SSBN) boats 05-08 began in the late 70s. Then, in 1982, a shipbuilder involvement contract for detailed design and build was placed with Vickers Shipbuilding & Engineering Limited's Barrow shipyard who immediately responded to the challenge.
The original Royal Navy Polaris-armed Resolution Class Ballistic Nuclear Submarines SSBN01-04 - the design of which had been adapted from the fleet nuclear submarine Valiant - had successfully maintained their strategic deterrence patrol continuously since 1968. The build programme for the new class of SSBNs was drawn up to ensure that each of the four purpose-designed Trident ballistic missile-carrying submarines
