Early war modifications involved replacing the after bank of torpedoes with a QF 12-pounder (3 inch/76 mm) anti-aircraft (AA) gun, cutting down the after funnel and mainmast to improve its field of fire and adding a pair of QF 20 mm Oerlikon guns in the bridge wings. Radar Type 286, a metric wavelength surface-warning set, was added as it became available and the ineffective multiple Vickers machine guns were replaced with Oerlikons; the central tube was deleted from the torpedo launchers to lessen topweight. "Icarus" lost 'Y' gun to stow extra depth charges (for a total load of 110) and their mortars. Surviving ships received a third pair of Oerlikons, added abreast the searchlight position and the 12-pounder was deleted to increase depth charge stowage. In some ships, 'A' gun was replaced with a Hedgehog forward-throwing A/S weapon but this alteration seems to have been reversed at a later stage. "Ilex", "Intrepid", "Impulsive" and "Isis" had 'B' gun removed and two QF 6-pounder 10 cwt (2.25 inch/57 mm L/47) guns were added on the twin mounting Mark I* along with a Hedgehog, the former for anti-E boat work.