The N class were ordered in 1940 as repeats of the J design, after delays and cost over-runs associated with the larger and more complicated . The only design change was to locate the 'X' 4.7-inch mounting in the more logical position with the 20° training blindspot forward. While building, the same early wartime modifications as the Js and Ks were applied, with a pair of twin power-operated 0.5 in machine gun turrets briefly carried on the quarterdeck before being replaced by single 20 mm Oerlikons.