The four Trident-armed SSBNs constitute the re-formed 1st Submarine Squadron based at the Clyde Submarine Base, HMS Neptune, Faslane, the facilities at which, together with those at RNAD Coulport, were upgraded and extended during a mammoth 10-year civil engineering project in readiness to receive the new Vanguard Class submarines from 1994.
As HMS Vanguard began her first deterrent patrol early in 1995, her predecessor HMS Resolution, built at Barrow in 1963-6, was duly withdrawn from RN service.
The Vanguard Class SSBN was designed to be operated by two crews and remain dived in its role of eternal vigilance for up to 16 weeks at a time, although SSBN07 began operating with one augmented crew from early 1997.
The major Trident Acquisition Programme was completed successfully in December 1999 by which time all four SSBNs had been delivered to and accepted by the Royal Navy. The estimated overall cost of the Programme including missiles was £12.52 bn.
