The Type 12 or Whitby-class frigates were a six-ship class of anti-submarine frigates of the Royal Navy, which entered service late in the 1950s. They were designed in the early 1950s as first-rate ocean-going convoy escorts, in the light of experience gained during World War II. At this time, the Royal Navy were designing single-role escorts and the Whitbys were designed as fast convoy escorts capable of tackling high-speed submarines. However, this made the Whitbys more expensive and sophisticated to produce in large numbers in the event of a major war, and so the Type 14 "utility" or "second-rate" anti-submarine frigate was developed to complement the Type 12. Although themselves rapidly outdated, the Type 12 proved to be an excellent basis for a series of frigate designs used by the British and Commonwealth navies for the next 20 years.