The 'Castle' class was intended as a series of six offshore patrol vessels for the Royal Navy, designed in response to criticism of the previous 'Island' class. In the event, only two ships were built, HMS Leeds Castle and HMS Dumbarton Castle; these had significant improvements over the 'Island' class - they are 300 tonnes bigger, more stable in heavy seas, 3 knots faster and are fitted with a large flight deck that is capable of supporting a Sea King. For brief periods, the ships can accommodate up to 120 troops. Their primary mission is to serve with the Fishery Protection Squadron, protecting both the fishing fleets and the oil and gas fields of the North Sea. In addition, they can also serve as minelayers, and have detergent spraying facilities on board for dispersing oil slicks. Since the Falklands War, one ship has been kept long term in the Falkland Islands as a guardship. Leeds Castle and Dumbarton Castle rotate the role on a three-yearly basis, although the ship's crew usually does a six month rotation. At present (2004), Leeds Castle is serving in the role. The 'Castle' class is to be replaced by a River class-based vessel, HMS Clyde.

Castle Class