In January 1963, the U.K. Defense Committee decided that four FBM submarines should be built, with an option on a fifth which was later canceled.
Number Submarine Name
SSBN-01 HMS Resolution
SSBN-02 HMS Renown
SSBN-03 HMS Repulse
The HMS Resolution (SSBN-01) deployed with POLARIS A3P on its first operational patrol in June 1968. Since 1968 the United Kingdom has deployed a force of four ballistic missile submarines (SSBN) each of 7,500 tonnes displacement, adapted from the then existing Valiant Class SSN, armed with Polaris missiles. This force conducted over 229 consecutive and continuous patrols.
The age of the force, and improvements in potential adversaries' capabilities, led the Government to upgrade the Polaris system. The replacement of Polaris with Trident has involved successive Resolution Class boats being retired as the larger Vanguard Class SSBNs entered service.