The 15 Inch Mark I BL Gun came into service with the Royal Nay as a battleship and battle cruiser gun in 1915, some 184 being produced in total. It became the longest serving of all British large gun designs, finally being retired from British service in 1960 when the last British battleship, the HMS Vanguard was scrapped. Vanguard had been in reserve since 1955.
Twenty five 15 Inch Guns served as coast artillery, eighteen with the Spanish armed forces, and seven with the Royal Artillery. Two of the British guns, named Clem (after Winston Churchill’s wife) and Jane ( a famous cartoon character), were near Dover, and fired on targets in France during WWII. The remaining five served in Singapore until they were spiked on the evening of 12 February 1942.
Of the five guns in Singapore, one was on a Mark I (Singapore) Mounting, with the remaining four on Mark II (Spanish) Mountings. The Mark I Mounting was specifically developed for Singapore and it was originally intended that all the Singapore guns would be on this type of mounting. A single Mark I Mounting was constructed for testing purposes at Shoeburyness in England during 1931/32 before being dismantled and sent to Singapore. Even then it was realised that the mounting built for Spain would probably be used in Singapore.
The small crane in the photo on the right above was used to bring ammunition up from the magazine should the loading mechanism break down. This would be directly behind the gun when it was aligned to centre of arc. The Singapore guns had two such cranes for each gun, one over the shell room, the other over the magazine. These were for lowering ammunition, but could be used to service the gun if required. From the 1950s, the Spanish guns had shells loaded automatically, but the propellant cartridges were brought up using the crane. This was after an accident in a magazine complex when a damaged cartridge was removed from the hoist, placed to one side and then somehow ignited. Some twenty men died in the accident.
The mounting sold to Spain had greater arc of fire, and the guns were also automatically loaded, whereas the Mark I mounted gun could not be. This meant that the Mark I mounted gun could only fire one round per minute compared to two rounds for the Spanish Mounting. The mountings and the magazines as used by Spain were modified in the light of experience, and renamed the Mark II (Spanish) Mounting. They were used used for the No.s 2 and 3 Guns of the Johore Battery, and both guns of the Buona Vista Battery.
There had been much discussion as to where to locate these guns in Singapore, and as to how many guns, before the figure of five was reached and the guns emplaced. Three were at Changi forming the Johore Battery, and two straddled the Ulu Pandan Road near its junction with Reformatory Road (Now Clementi Road), becoming the Buona Vista Battery. The Johore Battery had the sole gun on the Mark I Mounting, and this gun became the No.1 Gun of the Battery. Plans for a single 15-Inch Gun at Tanjong China on Blakang Mati were never came to fruition.
The 15-Inch Gun had a length of 52'5" (16 metres), and fired a shell weighing 1938 lb (879 kg). The shell left the barrel at 2,575 feet per second (785 metres per second. The guns at Singapore had an elevation of 45°, and a range of 36,900 yards (33,741 metres).
The Singapore guns were capable of a range of some 44,000 yards (40,233 metres) but were limited by the ranging instrumentation. A request, “essential for 15 inch batteries and desirable 9·2 inch batteries increase maximum range co-ordinate converter to 40,000 yards” was made to the War Office in London by the G.O.C. Malaya on 24 May 1941. The estimated cost was £12 per instrument, with parts being manufactured locally. This was approved on 30 May with the proviso that there be no loss of accuracy below 35,000 yards (32,004 metres). I’ve not as yet found any confirmation that this was actually done.