1:600 Kingfisher class corvette pre-war. In design they resembled a minature WW1 destroyer, and the armament of one 4" LA and 8 rifle calibre machine-guns to back up depth charges was totally inadequate © Andrew Arthur

1:600 Kingfisher class corvette early war, with the 4" LA replaced by a 4" AA gun, and a quad 0.5" MG added right aft on the quarterdeck © Andrew Arthur

1:600 Kingfisher class corvette HMS Shearwater, wartime. There is a 20mm AA in each wing, and a 2pdr. gun on each side aft. Later, SW type 27- RDF would be added abaft the bridge © Andrew Arthur

The 9 units of the "Kingfisher" Class of Coastal Patrol Boat - or, as they were later defined, Coastal Corvettes - were unique in the history of RN warship designs. Designed in the early 1930s, they were intended for combating an enemy submarine threat in UK coastal waters, and as such had a limited range and a main armament of depth charges.
In appearance they seemed to have the hull of a miniature WW1 destroyer, with a single low-angle 4" guns forward, an open box-like bridge and upperworks, a single raked funnel and depth-charges aft.
Like all designs "evolved" over a number of years, each ship joined the Fleet with slight changes in design and modifications incorporated as a result of experience gained in earlier ships. By the end of 1939 all ships had a covered bridge, and the low-angle gun had been replaced by a more modern H/A Mk.III 4" mounting. It was soon realised, after the opening of hostilities, that the class were woefully deficient in anti-aircraft defence; this was improved somewhat by the fitting of a quadruple 0.5" machine-gun right aft. As soon as they became available, one or two single 20mm Oerlikons were added, but the ships’ very limited displacement prevented any great addition to the defensive armament.
By 1942, most of the class had been fitted with SW type 271 surface search radar at the rear of the bridge.
All the ships had a very "active" war, suffering frequent damage whilst both on and off operations.