Development of the dual purpose (120mm) 4.7 inch L/55 twin turret had shown the difficulty of training a large gun at a fast moving aircraft. So all plans to make the 8" gun for treaty cruisers dual purpose were scrapped in favour of fitting the DP 4.7" guns as secondary armament. The simplified 8" twin turrets had a maximum elevation of 50° (to maximise range). This afforded a little more weight (lower turret) for the secondary armament and made the later Norfolk class cheaper to build. These classes were the first inter-war cruisers built and had enough range to be useful in the Pacific (based at Singapore or Hong Kong).
The Norfolk Class (Norfolk, Dorsetshire,
Northumberland,
Surrey, York and Exeter) were equipped with air conditioning (with long warm weather cruises in mind). They had no amidships magazine (Northumberland onwards) to allow a box citadel fore and aft of increased armour thickness (3").
As a result of the magazine changes, and to keep the funnels distant from the bridge, only two funnels were required; the forward boiler room uptakes trunked up into a large fore-funnel. This was raked in Northumberland-York to clear the flue gasses from the bridge, but was straight in Exeter owing to an altered bridge design and more extensive trunking. To maintain homogeneity of appearance, York stepped raked masts and Exeter vertical ones. York had a tall "platform" style bridge as seen in the Countys, which was somewhat distant from 'B' turret. This was because it had been intended to fit a catapult and floatplane to the roof of the turret, which needed clearance distance and required a tall bridge to provide forward view. The roof of the turret, however, was not sufficiently strong to carry this catapult and it was never fitted. Exeter was ordered two years later and the bridge was redesigned in light of this, being lower, further forward and fully enclosed, as later seen in the light cruiser classes.
The twelve, 7,500 tons standard, Leander Class light cruisers were designed to carry four twin
BL 6 in (152 mm) Mk. XXIII guns two aft and two forward, superfiring, on the centreline. Secondary armament consisted of four dual purpose 4.7 inch L/55 twin turrets. The later twelve Town class (HMS Southampton onwards) were a little heavier at 8,100 tons. They employed three triple
BL 6 inch Mk XXIII naval gun turrets (one aft) and the same secondary armament. The
Dido Class escort cruisers would go over to an entirely dual purpose armament with 8x 4.7 inch L/55 twin turrets (replacing the 6" twin turrets of the
Leander design with extra DP guns). Eight guns able to fire directly fore or aft, twelve to either side. At higher elevations it was often possible to train all sixteen guns on target. Later Escort Destroyers used 3" DP twin turrets as secondary armament with the advent of the proximity fuse.
All these cruisers were limited, by treaty, to 10,000 tons standard displacement. Escort, light and heavy refers more to the size of the main guns. Light AAA was a combination of twin 3" turrets and 2 pounder (40mm) guns.
Double and Triple 15"/42 gun turret production exceeds battleships and battle cruisers equipped to use it by 100%. There are three spare barrels for every turret.
Queen Elizabeth class battleships (Five ships with eight guns each)
Revenge class battleships (Five ships with eight guns each)
Renown class battlecruisers (Two ships with six guns each)
HMS Hood - battlecruiser (Eight guns)
Nelson-class battleships (Two ships with nine guns each)
Advanced post-
Hood/
Renown Battle Cruiser designs employing three triple turrets (one aft) make use of a further nine triple turrets.
The Queen Elizabeth Class were given new machinery, thicker armour, torpedo bulges, 4.7" DP turrets instead of their 6" guns and greater elevation of the 15" twin turret guns to 35°. Unable to update the Revenge class, they were replaced by five new battleships to a twelve gun design (four triple turrets) laid down in 1937 and commissioned in 1940 (
KGV Class) and were given a new role as barrage (NGFS) ships. Four
Ark Royal Class 22,000 ton aircraft carriers were laid down in 1934-1935 and commissioned in 1938-1939. One each for the Med and Far East fleets with two in the Home fleet. The
Glorious,
Hermes* (Far East),
Courageous, Eagle (Med) and
Furious, Argus* (Home) were already in service. So the smaller two(*) were taken out of service as training ships.
Hermes was later reintroduced as the first Depot Carrier that presaged the
Unicorn Class. HMS
Furious was refitted to
Courageous/Glorious Class standard.
That's 50 triple turrets (25 in use) and 100 double turrets (50 in use) for a total of 350 barrels, 175 in use.