Royal Navy Frigates

Development of the Royal Navy's postwar frigates began with the "1945 Frigate Concept". These developments include: the R.N's first Diesel-propelled frigates -HMS Salisbury, a Type 61 aircraft direction frigate laid down in January 1952, and Leopard, a Type 41 anti-aircraft frigate - which had the same design of hull and machinery and a speed of 25 knots (too low for an anti-submarine version).

The 30-knot Type 12 (Whitby class) A/S frigate had steam-turbine propulsion and a hull about 29 ft longer than the 25-knot ships, which was later slightly modified and extended as the Rothesay class (laid down in October 1952); the Type 14 (Blackwood class), a less powerful A/S frigate than the Type 12 and designed for quantity production; the Type 81 (Tribal class) general-purpose frigate, a design, finalised in 1957, in which the gas turbine, as a propulsion system component, was introduced into the R.N.;

The Modified Type 12 (the Leander class), of which 26 were built as GP frigates, with some were afterwards modified for the A/S role and, later, some for the ASUW (anti-surface warfare) role. The Type 21 was a commercial design with all gas-turbine propulsion, the contract for which was awarded, in 1968 to Vosper Thornycroft in cooperation with Yarrow Ltd - eight were completed in 1974-78. The Type 22 (leadship H.M.S. Broadsword), was an all-missile design with two helicopters for her primary A/S role and with secondary general-purpose capability. Some modifications were incorporated as a result of experience in the Falklands war, and later vessels were enlarged and mounted a medium-calibre gun.

Frigates and destroyers are collectively known as "escorts." What distinguishes a destroyer is its air defence missile system, which makes it three times as expensive as a frigate. Frigates are the ships and the capabilities which provide the fleet with its principal patrolling, maritime security, escorting, joint sea base protection and littoral effect capability. They are the glue which holds the Fleet together; the most visible face of maritime capability. In the absence of a new program, in 2017 the RN may have as few as six T-45s and the next youngest frigate will be fifteen years old.