The design of the
Lion-class battleships was influenced by the terms of several
arms control treaties of the 1920s and 1930s. The
Washington Naval Treaty of 1922 had banned new battleship construction, with certain specified exceptions, for a decade. The
London Naval Treaty of 1930 extended the ban for five more years, which meant that almost all the First World War-era ships would be eligible for replacement by the Washington Treaty's rules when the London Treaty expired. The British government intended for the 1935 Second London Naval Disarmament Conference to prevent a naval arms race that Britain could ill afford, but the Japanese refusal to sign the resulting
Second London Naval Treaty of 1936 thwarted that hope. The three signatories, Britain, France and the United States had agreed to limit the size and gun calibre for the battleships that would be built by the signatories. They were restricted to
standard displacement and a main armament
calibre of . This dictated the choice of the 14-inch gun for the main battery of the
King George Vs (KGV). The treaty contained an "Escalator Clause" that would increase the maximum allowable calibre to 16 inches if the Japanese government failed to sign; this was triggered in April 1937. As it was too late to modify the
KGVs to avoid delays in construction, the
Board of Admiralty then began preliminary design work on a 35,000-long-ton ship armed with 16-inch guns and it was promising enough that the
Director of Naval Construction (DNC) was ordered to further investigate such designs. To save design time, many of the features of the
KGVs were incorporated in the new design, but the limited size of the ship was a real challenge for the designers. Maintaining the same speed, protection, and secondary armament as the older ships while using 16-inch guns proved impossible while remaining within the treaty limits. In an effort to remain within treaty limits, the overall weight of armour was slightly reduced and two twin gun turrets as well as aircraft and their facilities were eliminated. The treaty-imposed design problems became irrelevant on 31 March 1938, when the signatories of the Treaty invoked the tonnage escalation clause because the Japanese refused to provide any information about their battleship construction programme and the signatories feared that their new ships could be outclassed by the new Japanese battleships. Due to limitations of docking facilities particularly at
Rosyth and
Portsmouth as well as costs, the Admiralty hoped to have the new limit at ; the limit was eventually settled at because the Americans would accept only that figure or none at all. The Admiralty in any case decided to limit itself to 40,000 long tons and nine 16-inch guns on the grounds that larger vessels would be unable to dock at the major Royal Navy dockyards at Rosyth or Portsmouth. A new design was prepared with more armour, more powerful machinery, the two twin 5.25-inch gun turrets restored, and four aircraft added. The Admiralty approved this design on 15 December and bids were solicited very shortly afterwards.
1938 design The 1938 version of the
Lion class had a
waterline length of , an
overall length of , a
beam of , and a maximum
draught of . They would have displaced at standard load and at
deep load. In the interests of saving time, the four-shaft unit machinery design from the
KGVs was duplicated with alternating boiler and engine rooms. The
Lion-class ships would have had four sets of geared
Parsons steam turbine sets housed in separate engine rooms, each driving one
propeller shaft. They were designed to produce a total of at overload condition and a speed of . The turbines were intended to be powered by eight
Admiralty three-drum boilers in four
boiler rooms at a working pressure of and temperature of . The turbines and boilers could be cross-connected in an emergency. The ships were designed to carry of
fuel oil. Their maximum estimated range was at a speed of . They would have been equipped with six
turbogenerators and two 330-kW
diesel generators that supplied the common
ring main at 220
volts. The
Lion-class ships' main armament consisted of nine newly designed 45-
calibre BL 16-inch Mark II guns in three hydraulically powered triple-gun turrets. and the ships carried 100 shells per gun. The secondary armament consisted of sixteen 50-calibre
QF 5.25-inch Mk I dual-purpose guns in eight twin-gun mounts. and 400 rounds were provided for each gun. Short-range air defence was provided by 48
QF 2-pounder "pom-pom" guns in six octuple mountings. and 1,800 rounds per gun were carried by the ships. The
Lion-class ships would have had a
double bottom with a depth of . Naval historians William Garzke and Robert Dulin believe that the design of the
Lion class would have corrected some of the deficiencies of the
KGVs with the notable exceptions of the too-shallow torpedo protection system, caused by limits of the existing infrastructure, and the limited endurance, both of which were addressed in the revised 1942 design. Their 16-inch main battery, although not the most powerful in the world, were superior to the earlier guns used in the s, and they "would have been the most powerful and fastest battleships to have served in the Royal Navy."
1942 design Construction was suspended shortly after the war began and the Admiralty took advantage of the time to refine the design in light of war experience in late 1941. The beam was increased to , the maximum width allowed by the
locks of the
Panama Canal, to increase the depth and effectiveness of the ships' torpedo protection system, and almost of fuel oil were added to increase the ship's endurance. The beam increase meant that many of the Royal Navy home docking facilities, including Rosyth and Portsmouth, could no longer accommodate these ships. The requirement that 'A' turret had to be able to fire directly ahead at 0° elevation was rescinded as it radically reduced
freeboard forward and caused the
KGVs to take a lot of water over the bow in
head seas. To partially compensate for the additional weight, the belt armour was reduced in thickness by to except over the
magazines, and the aircraft and their facilities were removed. The space in the superstructure freed up by these changes was used to increase the light anti-aircraft armament to nine octuple and one quadruple 2-pounder mounts. The overall length of the
Lion class increased to and the displacement grew to at standard load and at deep load. No changes were made to the propulsion machinery, but the speed decreased to because of the greater displacement. The of fuel increased their endurance to an estimated maximum of at a speed of 10 knots. The freeboard forward was increased by nearly , and the radar suite was increased to match that of the battleship , then under construction. Because the
light cruiser lost all steam power when she struck a
mine early in the war, two diesel generators were substituted for two
turbo-generators. The extra beam was used to increase the depth of the torpedo protection system amidships from 13.25 ft to . The ships' crew was estimated at 1,750 officers and ratings.
1944 design The RN's Plans Division set a requirement for a dozen battleships for the post-war navy and the DNC began another design in February 1944 that would incorporate wartime lessons, but they soon concluded that "the power of modern weapons had increased so much that ever-increasing armour and torpedo protection was required until it became incompatible with the limited offensive power of the ship." The main armament was revised to an improved Mk IV version of the 16-inch gun in a new Mk III turret that fired a heavier shell at a marginally lower velocity, mounted in three triple turrets. They would also carry twelve twin
QF Mk V guns as their secondary armament and one twin and ten sextuple Bofors mounts plus fifty 20 mm Oerlikons for anti-aircraft protection. Calculations for a preliminary sketch design were completed in October and revealed a , ship at standard load and at deep load. More detailed studies were conducted in January 1945 and showed that the ship would actually displace at standard load and deep. This design was too large, so multiple variants were considered over the next several months, examining the effects of reducing side armour, underwater protection and the number of main and secondary gun turrets. The provisional staff requirements were issued in March and increased the speed to and set the endurance equal to that of the original design, which was slightly modified in April as 'Design B'. This greatly hampered the ability of the designers to reduce the size of the design as only those variants with two main gun turrets were below at standard displacement. The most radical variant, christened 'Design X', had an armour arrangement similar to the modernised
battlecruiser with a pair of 16-inch and eight 4.5-inch turrets and had only minimal underwater protection, relying on tight compartmentalisation and strengthened internal bulkheads to localise damage. This yielded a ship at standard load. That same month a committee headed by
Rear-Admiral Reginald Servaes reviewed all the proposals and the Admiralty requested a sketch design of 'X' with two 16-inch turrets, both forward of the
superstructure as in the French , and a thicker waterline belt in May that the DNC designated 'X3'. This displaced at standard load. The following month the Admiralty asked that the 16-inch turrets be replaced by quadruple turrets and the DNC replied that no design work had been done on such turrets and would thus delay construction by 15 to 18 months and add about to the ship's displacement. The DNC asked permission to investigate further methods of reducing the size of 'B3' in July and work continued on both designs through October. By this time the impossibility of even maintaining the existing battle fleet, much less building such large battleships, had become clear in light of Britain's economic difficulties and further design work was informally suspended on all but the new Mk IV gun and its Mk III turret; this was finally cancelled by the
First Sea Lord on 10 March 1949.
Hybrid aircraft carrier On 8 January 1941, Rear-Admiral
Bruce Fraser,
Third Sea Lord and Controller of the Navy, asked the DNC to work up a hybrid aircraft carrier based on the
Lion-class hull. Two months later, a sketch design was presented for consideration, but it was not well regarded by the participants. This design retained all three main gun turrets and the flight deck was deemed too short to be useful. A revised version with only the two forward turrets retained was requested and was ready in July. In this design, the displacement ranged from at standard load and at deep load. The design's dimensions included a waterline length of , a beam of and a draught of . The flight deck was long and had a width of . The machinery was unchanged, but another of oil increased her endurance to at 10 knots. The hybrid's armament consisted of six 16-inch guns in two triple turrets, sixteen 5.25-inch guns and eight octuple 2-pounder mounts. Twelve
fighters and two
torpedo bombers could be carried. The Director of Naval Gunnery's assessment was that "The functions and requirements of carriers and of surface gun platforms are entirely incompatible ... the conceptions of these designs ... is evidently the result of an unresolved contest between a conscious acceptance of aircraft and a subconscious desire for a 1914 Fleet ... these abortions are the results of a psychological maladjustment. The necessary readjustments should result from a proper re-analysis of the whole question, what would be a balanced fleet in 1945, 1950 or 1955?" The design was rejected. ==Construction==