"London" had a main battery of four 40-calibre guns mounted in twin-gun turrets fore and aft; these guns were mounted in circular barbettes that allowed all-around loading or elevation. The ships also mounted a secondary battery of twelve 45-calibre guns mounted in casemates, in addition to sixteen 12-pounder guns and six 3-pounder guns for defence against torpedo boats. As was customary for battleships of the period, she was also equipped with four torpedo tubes submerged in the hull. The tubes were placed on the broadside, abreast of the main battery barbettes.