The Type system is a classification system used by the British Royal Navy to classify surface escorts by function. The system evolved in the early 1950s, when the Royal Navy was experimenting with building single-purpose escort vessels with specific roles in light of experience gained in World War II. The original (July 1950) numbering scheme was:

Type 1X were Anti-Submarine (ASW) frigates (when the numbers ran out in the 1960s, ASW frigates continued as the Type 2X series).

Type 3X were General-Purpose (GP) frigates (Chosen 2015)
Type 4X were Anti-Aircraft (AAW) frigates (this later evolved into the "Destroyer" Type series).
Type 6X were Aircraft-Direction (ADW) frigates.
Type 8X were multi-role ships. An Admiralty Fleet Order defined these ships as "destroyers" if they could achieve "fleet speed" or as "sloops" if they could not.^[1]

Types 11-30, anti-submarine frigates

• Type 11 : Diesel powered anti-submarine frigate based on hull of Type 41 / 61. Not built.
• Type 12 Whitby-class : Steam powered, high-speed "first-rate" anti-submarine frigate.
• Type 12M Rothesay-class : Modified Type 12 design.
• Type 12I Leander : Improved Type 12, general purpose frigate. Also produced as the Condell class, River class, Nilgiri class and Van Speijk class for other navies
• Type 14 Blackwood : Steam powered, high-speed, "second-rate" anti-submarine frigate.
• Type 15 : High-speed anti submarine frigate, produced by full conversion of wartime built destroyers of the R-, T-, U- and V- and W and Z-classes.
• Type 16 : High-speed anti submarine frigate, produced by a limited conversion of wartime T-class (7 ships), O- and P-class (3) destroyers.
• Type 17 : "Third-rate" anti-submarine frigate, analogous to wartime corvettes. Design abandoned in 1953 and not built.
• Type 18 : High-speed anti submarine frigate, intermediate conversion of wartime destroyer hulls of the N-, S-, T and Z- classes (and intended to replace the Type 16). Design abandoned in 1953 and not built.
• Type 19 : Very high speed (42 knot) gas turbine powered anti-submarine frigate. Design abandoned in 1965. Not built.
• Type 21 Amazon-class: General purpose, gas-turbine powered commercially designed frigate.
• Type 22 Broadsword-class : Large, gas-turbine powered, anti-submarine frigates.
• Type 23 Duke-class : Gas-turbine and diesel powered, anti-submarine frigates. Smaller and less expensive than the Type 22, with similar capabilities. 16 built.
• Type 24 : Cheap frigate design ("Future Light Frigate") intended for export. In RN service would have served as a towed array ASW ship. Not built.
• Type 25 : More capable development of the Type 24, designed to have almost the capability of a Type 22 but at only three-quarters of the cost. Much of the thinking, including the diesel-electric machinery, went into the Type 23. Not built.
• Type 26 : "Global Combat Ship" : First announced in March 2010, and formerly known as the Future Surface Combatant. Initial orders placed in February 2014.^[2]

Types 31-40, general purpose frigates

• Type 31 : The Type 31 frigate is the proposed General Purpose frigate as set out in the Strategic Defence and Security Review 2015.^[3]
• Type 32 : The Type 32 frigate was mentioned in November 2020 as a future frigate.

Types 41-60, anti-aircraft frigates/destroyers

• Type 41 Leopard-class frigate : Diesel powered anti-aircraft frigate built on common hull with Type 61.
• Type 42(i) East coast frigate : High speed coastal escort. Not built
• Type 42 destroyer (ii) Sheffield-class : Gas-turbine powered, fleet area-defence anti-aircraft destroyer.
• Type 43 destroyer : Large gas-turbine powered, "double-ended" (Sea Dart launchers fore and aft), fleet area-defence anti-aircraft destroyer. Project cancelled in 1981 with none built.
• Type 44 destroyer : A smaller version of the Type 43 with better anti-submarine capability. Cancelled.
• Type 45 destroyer Daring-class : Fleet area-defence anti-aircraft destroyer to replace Type 44 project. 6 built.

Types 61-80, aircraft direction frigates

• Type 61 Salisbury-class : Diesel powered aircraft-direction frigate built on common hull with Type 41.
• Type 62 : Proposed high-speed aircraft-direction frigate, to be built by full conversion of five remaining ships of the M-class destroyers and seven War Emergency Programme destroyers. Not built.

Types 81-99, general purpose frigates/destroyers/sloops

• Type 81 Tribal-class frigate : Single-shaft steam / gas-turbine powered general purpose "colonial" frigates. Originally sloops reclassified as "second class" general-purpose frigates in 1960s.
• Type 82 destroyer : Large steam / gas-turbine powered fleet anti-aircraft and anti-submarine destroyer to replace County-class destroyers and escort CVA-01 aircraft carriers. Cancelled along with carriers. Only HMS Bristol (D23) was built of the four planned.
• Type 83: proposed in the 2021 Defence Command Paper as the successor to the Type 45 Destroyer entering service in the late 2030s.