She and her sisters; Sussex, Shropshire, and Devonshire differed from the earlier group of Counties (known as the Kent class) by having a smaller forward superstructure, which was positioned slightly further aft, and little armour plating.

London and her sister ship Shropshire facilitated the evacuation of thousands of civilians from Barcelona during the Spanish Civil War.

London then spent from March 1942 to November 1942 in the North Atlantic on convoy protection duties in the company of several US Navy warships.

After sea trials and loading of ammunition, she was assigned to operate off the South African coast and then to the Eastern Fleet for the rest of the war.

Following the Second World War, and being the Royal Navy's only modernised 8-inch gun cruiser, London was refitted for further service in early 1946 to allow her to serve in the postwar fleet.

London was surveyed to determine if an extensive repair and refit for further service was feasible, but the condition of her machinery (dating back to 1928 and not replaced during her rebuild in the 1930s), as well as the large crew she required made her too expensive a proposition, given Britain's post-war financial difficulties.