The Island-class patrol vessel was first designed and built for the Scottish Fisheries Protection Agency. As a result of the Royal Navy's experiences in the Cod Wars with Iceland, FPV Jura and FPV Westra were put in fishery protection patrols, the Navy built a further seven. These ships were designed and built by Hall Russell of Aberdeen, Scotland.

The Castle class was a class of British offshore patrol vessels of the Royal Navy. Two ships were constructed and after nearly 30 years service were sold to the Bangladesh Navy in 2010. The Bangladesh Navy upgraded these with more armaments including C-704 anti-ship missiles and sensors. These ships are now reclassified as corvettes by the Bangladesh Navy.