A Type 272 search radar and a HF/DF radio direction finder rounded out the Castles' sensor suite. They were equipped with Type 145Q and Type 147B ASDIC sets to detect submarines by reflections from sound waves beamed into the water. Provision was made for a further four single mounts if needed. The ships were fitted with two twin and a pair of single mounts for 20-millimeter (0.8 in) Oerlikon light AA guns. This was backed up by one depth charge rail and two throwers for 15 depth charges. The Castle-class ships were equipped with a single QF 4-inch (102 mm) Mk XVI gun forward, but their primary weapon was their single three-barrel Squid anti-submarine mortar. The ships' complement was 99 officers and ratings. The Castles carried a maximum of 480 long tons (490 t) of fuel oil that gave them a range of 6,500 nautical miles (12,000 km 7,500 mi) at 15 knots (28 km/h 17 mph).

The engines developed a total of 2,880 indicated horsepower (2,150 kW) and gave a maximum speed of 16.5 knots (30.6 km/h 19.0 mph). They were powered by two 4-cylinder triple-expansion steam engines, each driving one propeller shaft, using steam provided by two Admiralty three-drum boilers. The ships had an overall length of 252 feet (76.8 m), a beam of 36 feet 9 inches (11.2 m) and a deep draught of 14 feet (4.3 m). The ships displaced 1,010 long tons (1,030 t) at standard load and 1,510 long tons (1,530 t) at deep load. The Castle-class corvette was a stretched version of the preceding Flower class, enlarged to improve seakeeping and to accommodate modern weapons. Flint Castle remained there until she was taken out of service in March 1956 and broken up beginning in July 1958. The ship then became an anti-submarine training ship in Rosyth and Campbeltown, Scotland, before moving to Portland at the beginning of 1947. That month, she joined Escort Group B3 to escort convoys between Canada and Britain and continued to do so until the end of the war in May 1945. Flint Castle was transferred to Escort Group B2 in March and screened convoys to and from Gibraltar until September. After repairs were completed the following month, she was briefly assigned to the 39th Escort Group for convoy escort duties in the Atlantic Ocean. Completed at the end of 1943, the ship ran aground while training in January 1944. HMS Flint Castle (K383) was one of 44 Castle-class corvettes built for the Royal Navy during World War II. 15 × depth charges, 1 rack and 2 throwers.1 × 3-barrel Squid anti-submarine mortar.2 × twin, 2 × single 20 mm (0.8 in) Oerlikon light AA guns.

Flint escort