The Fort Record Book lists the following expected forms of attack:
(i) Deliberate Cruiser attack to damage Lowestoft (navigation risks are substantial in this area and this method of attack was considered unlikely)
(ii) Mass attack by motor torpedo boats, flying boats and small craft supported by parachute troops in order to seize the port of Lowestoft.
(iii) Full invasion – heavy air raids, motor torpedo boats and mine sweepers followed by troops arriving in successive waves regardless of loss. Invasion flotillas would be preceded by barrage breakers, minesweepers, dive bombers and E Boats.
(iv) Destroyer attack under smoke screen.
(v) Aircraft laying mines near harbor entrance.
(vi) Long range bombardment outside range of Coastal Defence guns.
Plan of Grand Hotel
The guns and mountings were brought from Lowestoft station by lorry. The mounting (pedestal, cradle and carriage) were transported in one piece. A Gyn was used to raise the carriage etc clear of the lorry and to lower it onto skidding. The Gyn was then re-arranged and the carriage raised and positioned over the holding down bolts then lowered down. The gun was lifted from the lorry by the Gyn and lowered onto skidding which was the right height to enable it to be run into the cradle on rollers running on track made of 6 ft planks.
The battery was constructed by Messrs T Gill & Son, Norwich. The magazine was constructed on a 12” concrete raft, finally covered with asphalt. On this the 6” magazine floor proper was constructed. No expansion points were provided for in the roof and large cracks appeared. The gun houses were constructed on a non-rigid principle of girders, brick and reinforced concrete. The roof consisted of plastic armour slabs.
The gun houses were camouflaged with tubular scaffolding supported canopies with nets /Dannert Wire garnished with artificial vegetation. A pergola passage connecting the two guns was similarly camouflaged.
The battery was connected to the town’s water mains. Emergency water supplies were held in two 100 gallon tanks and 16 two gallon cans (to be filled on ‘Stand To’). The Medical Officer of Health, Lowestoft, was in charge of medical arrangements. Walking wounded were to report to the nearest Civil First Aid Post (The Clinic, Southwell Road) while requests for ambulances for lying wounded were to go through the Civil Report Centre.
Accommodation under normal conditions was in three rooms on the 1st floor, north wing of the Grand Hotel. On ‘Action Stations’ all personnel would move to within the Battery area and accommodation would be in Duty and Reserve Watch shelters behind the guns, the Search Light Emplacements, Engine Room and Battery Observation Post.
Distribution of Fire
Distribution of fire was by the sequence system. In the above diagram the first three scenarios are self explanatory. In the fourth case, at night the system is illustrated as follows. No 1 searchlight picks up a target and both guns engage it. No 2 searchlight completes its sweep and then transfers onto the target which is engaged by No 2 gun while No 1 locates a new target which is engaged by No 1 gun. The leading target is disabled, No 2 searchlight takes over the second target (still engaged by No 1 gun). No 1 searchlight illuminates a third target which is engaged by No 2 gun.
Above: Arc of fire
During day light the battery would not open fire any a vessel unless instructed to by Fire Control. The battery would however open immediate fire on any submarine or motor torpedo boat, (even if the correct recognition signal was given) of which no information had been received. Such instructions would be suspended in periods of rough weather when British motor torpedo boats may not be able to give an expected arrival time (the battery would be notified of any suspension).
During the night the battery commander would not await instructions from Fire Control but would open fire on any vessel for which no information had been received (as no vessel was allowed to proceed within three miles of the coast except by previous arrangement).
For close defence the battery Fort Record list four Bren guns, four Sten guns, 166 No 36 grenades, 96 Molotov cocktails and two Spigot mortars. A Home Guard Garrison of two officers and 80 other ranks would be available at ‘Stand To’. Ammunition for the two 6” guns is listed as: 264 6” 4 C.R.H Lyddite HE (with 200 45P fuzes, 40 44 fuzes and 24 230 fuzes) and 60 CPC (fuzed No. 15).
Aerial - WO192/59
Above left: Map of local Infantry Defences. Above right: aerial of Grand Hotel Battery
A full record of test shooting exists for this battery:
As well as these test shoots, there were occasional firings at full charge to test the mountings.
Guns: Two 6” Mk XIII on P XI mountings.
Rangefinders: D.R.F - Mk II*B. No. 95; max range 10,000 yards; min range 1,500 yards.
CASL: No 1 – One projector, AA 90 cm Mk VI
One lamp AA Mk V
One reflector paraboloid 90/42
CASL: No 2 - One projector, AA 90 cm Mk V
One lamp AA Mk V
One reflector paraboloid 90/42
Engine room: - three 22 kw (AA) Lister Generating Sets
Above left: BOP Post, Grand Hotel (now CEFAS Building). Right: One of the gun houses now a store for grounds keepers.
Grand Hotel Fort Record Book, TNA