Major-General F.W. Barron visited Singapore in 1935 in order to report back to London on the defences of the island. He first held a meeting, on 26th February, at Fort Canning with senior officers, including the GOC, Major-General E.O. Lewin. At this meeting he outlined the objects of his visit. These included; “Whether the siting of the fixed defences produces the maximum of efficiency.” and “Additional fixed defences required for the 2nd Stage (of the upgrade of defences) and where they should be sited”. On the 11th March he reported to the GOC and senior officers. His report included a recommendation for two additional two gun 6 Inch Close Defence Batteries to be constructed in the Keppel Harbour Area. One of these should be at Pasir Panjang (Labrador) and, “One 6” Battery on SERAPONG Spur, making use of the old 9·2” emplacements and magazines”. The 9·2-Inch BL Spur Battery Emplacement would be modified for a Mark VII 6 Inch BL Gun as would the Magazine. This new gun was to become the No.1 Gun of the Battery. The No.2 6 Inch BL Gun Emplacement and its Magazine would be built 50 yards (46 meters) north-west of the Spur position. The 9·2-Inch Battery Command Post for the Spur Battery which was 50 yards north west of the new No.2 Gun would be enlarged to make the 6 Inch Battery Observation Post.
An edict issued in 1937 stated that all eighteen 6 Inch BL Guns and six 9·2-Inch BL Guns in Singapore were to have all round traverse. This is how the new Serapong Battery with its Mark VII 6 Inch BL Guns and their Mark II 15° CPMs was built. The guns were fitted with the low Mark I Shield. Some time later,probably in 1941, overhead semi-circular concrete splinter protection was constructed at the Serapong Emplacements.
LEFT: The Serapong 6-Inch Battery in 1939. The photo was taken from a roof of a building between the No.2 Gun and the Battery Observation Post. Concrete overhead splinter cover was added to each gun emplacement circa 1941.
When war came to Singapore and Malaya in 1941, the Serapong and all other coast batteries stood ready to fend off a seaborne attack which would never come. On the 18th January 1942, the Serapong Battery was bombed with the No.2 Gun and its concrete splinter cover being damaged. The gun itself was replaced from Reserve. Other bombs fell elsewhere on Mount Serapong, close to the Battery Observation Post for Fort Connaught, and on Fort Connaught itself.
There is no record of the Serapong Guns firing on the advancing Japanese. The guns arc of fire is given in records as being from 20° to 270°, a sweep of 250°. This figure may have been correct before the overhead cover was installed, however the cover would restrict the sweep to around 180°, or even less. An angle of 20° would mean that the left of arc would past just east of Elgin Bridge and on over the Serangoon Active SG Swimming Complex to the top of Yio Chu Kang Terrace. 270° would go to a point to a point south east of Tuas Naval Base.
The location of the battery and the overhead cover would have prevented it firing to the west where the Japanese were advancing from Pasir Panjang and Kent Ridge. However, it would have been possible for the guns to fire eastwards towards the Kallang area. Even if the guns had taken part in the war, there is little they could have done to repel the Japanese. The ammunition, being mainly AP was totally unsuitable for counter-battery and anti-personnel fire. The guns however, did fire shots across the bows of ships which were inadvertently heading into the minefields protecting the harbour. At least one ship sank after straying into a minefield.