The sides of the conning tower were 11 inches thick and it had a 3-inch roof of KNC. It had a communications tube with 8 inch walls of mild steel down to the Transmitting Station on the middle deck. The walls of the signal tower were 8 inches thick while it had a roof of 3 inches of KNC armour. 2 inch torpedo bulkheads were fitted abreast the magazines and shell rooms of 'A', 'X' and 'Y' turrets, but this increased to 4 inches abreast 'P' and 'Q' turrets to compensate for their outboard location.