 The woeful lack of defensive armament was addressed early in the war by adding a multiple Vickers machine gun on the quarterdeck in the "Kingfisher" and "Kittiwake" groups, as per the "Shearwaters".As they became available, two single 20 mm Oerlikon guns were added, on single pedestal mounts on the deckhouse aft, with the useless machine gun being replaced later with a further pair of such weapons.Centimetric Radar Type 271 was added on the roof of the bridge as it became available, this was a target indication set capable of picking up the conning tower or even the periscope or snorkel of a submarine.