The Type 81, or Tribal class, frigates were ordered and built as sloops to carry out similar duties to the immediate post war improved Black Swan-class sloops and Loch-class frigates in the Persian Gulf. In the mid 1960s the seven Tribals were reclassified as second class general-purpose frigates to maintain frigate numbers. After the British withdrawal from East of Suez in 1971 the Tribals operated in the NATO North Atlantic sphere with the only update the fitting of Seacat missiles to all by 1977, limited by their single propeller and low speed of 24 knots. In 1979-80 age and crew and fuel shortages saw them transferred to the stand-by squadrons; three were reactivated in 1982 during the Falklands War for training and guardship duties in the West Indies.