Mk 24 was an entirely new single mount designed by Northern Pump specifically for merchant ships. It was simplified by replacing the earlier hydraulic recuperator with a counter-recoil spring wound around the barrel, as shown here. Mk 24 in turn was the basis for the automatic 3in/50 produced as an anti-Kamikaze measure at the end of the war.
The 3in/23 Mk 14 mounting. (Photograph by Richard S Pekelney, Historic Naval Ships Association, courtesy of Mr Pekelney)
Background
Once it had defeated Germany, the Royal Navy’s outlook on future war changed dramatically. With minor exceptions, from about 1919 on attention focussed on Japan. Although the Japanese had proven helpful during the First World War, they had also shown an appetite for the British Far Eastern empire, as well as for the informal or commercial empire in China. Ideally the British would have stationed a powerful fleet in the East as a deterrent, but the available infrastructure was far too limited. The most ambitious plan was to send the battlecruisers east in 1929, and that had to be cancelled. Instead, the fleet had to be split between the Mediterranean and Home waters. In a crisis the Mediterranean Fleet would steam to Singapore, which was thought to be well beyond the range of Japanese land-based aircraft. Singapore would be the Scapa Flow of a Far Eastern war, the fleet there either forcing the Japanese to remain at home (as the Grand Fleet had bottled up the German High Seas Fleet) or fighting a decisive action. Ideally the fleet would steam to Singapore as tensions rose but before war broke out.
As in the US planning described in the next chapter, the decisive stage in the war would be a close blockade of Japan, which depended almost entirely on imports for survival. To mount the blockade, the British would have to destroy the Japanese fleet in a decisive action. Because the British expected to fight far from any Japanese land bases, they could imagine that air attack during the run-up to the big battle would be extremely limited (the US Navy was in a different position). Any attacks would be mounted by shore- or sea-based long-range aircraft, at ranges which would automatically limit the scale of the attack. Thus the main threats to the fleet prior to the fleet battle would probably be Japanese submarines and Japanese-laid mines. Mass air attacks would be limited to carrier air strikes mounted either just before or during the fleet action.
In 1935 the situation was transformed. British faced a real threat of war against Italy during the crisis over Abyssinia. Massed long-range land-based Italian aircraft were suddenly a credible threat, as was the large number of Italian motor torpedo boats. It was impossible to deal with land-based aircraft by a pre-emptive strike (which might, for example, eliminate a threat further out to sea by sinking the enemy’s carriers). The motor torpedo boats affected British anti-aircraft thinking because light anti-aircraft guns were conceived both to fend off close-range air attacks and also to deal with motor torpedo boats. British understanding of the air threat at the time of the 1935 crisis naturally reflected the recent committee report, and much of what was done on an emergency basis responded to its recommendations. The exception was the decision to convert old light cruisers to specialist anti-aircraft ships, a step the committee had explicitly rejected.
For the inter-war Royal Navy, the key facts of life were limited carrier capacity, in terms of numbers of aircraft, and the limited number of carriers prescribed by the Washington Treaty in 1921. Aircraft carrier capacity was set, the Royal Navy thought, by hangar capacity; aircraft were not to be kept on the flight deck after they landed. There was some interest in the US style of operation about 1931, but by that time it seemed that a new arms limitation treaty might control overall numbers of military aircraft, and the RAF stoutly resisted any increase in rated carrier capacity. This equation explains why Ark Royal was designed in 1933 with two hangars. The Royal Navy adopted deck parks only during the war, and it largely abandoned them after it. The Royal Navy was well aware of what air strikes could achieve: it wanted as many strike aircraft as it could get. In the early 1930s it fastened on a solution: cruisers and battleships would carry strike aircraft armed with torpedoes. The same type of aircraft would fly off carriers. This combination of requirements created the Swordfish. It needed maximum lift to fly from a catapult with a 60kt end speed carrying a torpedo, for the strike role. It needed maximum scouting range because the Royal Navy lacked a long-range shore-based air arm like the flying boats of the US and Imperial Japanese navies. That favoured the relatively low-powered engine available when the aircraft was designed (the 1000hp class engines suited to tactical aircraft appeared about two years later). The Swordfish was designated a TSR, a torpedo-spotter-reconnaissance aircraft. In theory, then, it could find an enemy fleet, slow it enough (using torpedoes) to allow the slower British battle line to catch up, and then support the gunnery action by spotting for the capital ships. The Fleet Air Arm motto was ‘Find, Fix and Strike’, and the British concluded after Jutland that enemy battle fleets might well try to evade their own slower but very powerful battle line. Fixing meant slowing them enough that evasion would become impossible (the new heavy shells issued after Jutland were intended for much the same purpose, to disable any German capital ship machinery they hit badly enough that they could never escape again). The low take-off and landing speeds of the Swordfish turned out to be a great virtue when it operated from small escort and merchant aircraft carriers, and it was one of the few combat aircraft to operate throughout the Second World War. These Swordfish, photographed in 1944, carry underwing rocket rails with which to attack U-boats. (David Hobbs)
Queen Elizabeth was subject to a more complete modernisation than Warspite, the main difference being that she received a uniform secondary battery of 4.5in guns in the new BD mounting which had been under development since the 1920s. The turret-top guns are twin power-driven Oerlikons. Unlike later battleships, she could not accommodate more pom-poms in addition to the four installed on modernisation. She is shown off Hampton Roads after a US refit, 2 June 1943.
Throughout the inter-war period, the Royal Navy tried to maintain a modern fleet by adding weapons and equipment on a step by step basis. The basis of anti-aircraft fire control, the HACS, came first, because once it was in place medium-calibre guns could be added as required. Photographed in 1934, Ramilles shows what was done before the major fleet rearmament begun in 1936. She has a HA director atop her foretop, an octuple pompom (on the platform abeam her funnel, under the two searchlights), and four 4in guns Mk V. These upper-deck guns were relatively easy to replace later with twin mounts, because neither they nor the twins was power-driven or penetrated the upper deck. The major pre-war upgrade to this and similar ships was to replace the single guns with twins.
Warspite was subject to an elaborate modernisation which provided her with the standard automatic battery of a modern capital ship: four octuple pompoms. She also had sided HA directors, so that she could engage attacks from both sides simultaneously (less modern battleships with a single director could not do so). She was also given the new quadruple 0.5in machine guns, which are visible atop her superfiring turrets. The coloured stripes on ‘B’ turret were added during the Spanish Civil War, to indicate to the combatants that she was part of the neutrality patrol. Note that the pom-poms were not shielded.