Zone économique exclusive
The Island-class was the result in the increase in the United Kingdom's Exclusive economic zone to , with a resulting increase in the requirements to patrol fishing grounds and oil fields. After evaluation of the Scottish Fisheries Protection Agency's fishery protection vessel "Jura", built by the shipbuilders Hall, Russell &amp; Company to a trawler-like design, the Royal Navy ordered five ships of the Island-class, based on "Jura"s design in February 1975, with a further two ships, "Anglesey" and on 21 October 1977.