The Home Forces Coast Defence Committee first met on 17th Jan 1941.The object of the first meeting was to decide what scale of Coast artillery, apart from defended ports, was required to meet an invasion threat. An assessment was also made on the priority for siting new equipments, and should the Navy require the return of guns, the priority in which they should be withdrawn.
The following assumptions were made about any invasion attempt by the Committee:
The coast between Kinnaird’s Head and Dungeness could face a full scale invasion attempt, supported by units of the enemy fleet up to battle ships, but it was considered no ships larger than cruisers would be used between Flamborough Head and Dover and in the Channel.
Barges would only likely be used between the Wash and Portland. Outside these areas, specially adapted merchant ships and specially built tank landing craft would be used.
The enemy air force would only be able to give initial support of any landing between the Wash and Bristol.
Any threat of invasion between Milford Haven and Moray Firth was negligible unless preceded by an invasion of Eire.
The Germans would require at least 6,000 yards of beach on which to land an armoured division.
A total of 30 ships and 24 tank landing craft would be required to land a “cut down” armoured division. These ships would run straight onto the beach and unload troops and cargo over the bows. At least three hours would be required to complete the landing.
4” guns were ineffective against merchant ships; the minimum size should be 6”.
Correspondingly, the coast was divided into in to four priority areas:
First Priority: Wash to Isle of Wight (liable to a full scale attack supported by fighters). A minimum of one 6” gun per 1,000 yards of beach was required for First Priority areas.
Second Priority: Isle of Wight to Milford Haven (liable to a reduced scale of attack but still with fighter support). An allowance of 75% of guns of First Priority areas was considered necessary.
Third Priority: Kinnaird’s Head to the Wash (liable to a full scale attack but without fighter support). An allowance of 50% of guns of First Priority areas was considered necessary.
Forth Priority: Kinnaird’s Head to Milford Haven (not liable to an attack unless Eire invaded first but still liable to raids). Specific consideration for guns was only to be given to areas liable to raids.
As a result of these assumptions, the Committee produced a schedule of the number of 6” guns required in addition to those already in place - a total of 190 additional guns! In Suffolk, it was considered an additional 18 6” guns would be required between Lowestoft to Leiston and four 6” guns in the Felixstowe area. It was realized this scale of issue would not be achieved for at least two years.
However, as at February 1941, only 10 5.5” guns, 18 6” guns and eight 7.5” guns were available for immediate allotment. There were also an additional 12 6” guns for which no ammunition would be available for six months and about 30 French 5.4” guns which would be available by May 1941.Of the 18 6” guns available, Suffolk received four (Kessingland and Minsmere batteries). Harwich was considered for some of the 7.5” guns (to be sited at areas were big ships might come close to close range) but it was thought that nothing larger than a cruiser would attack.
During April it became increasingly likely that the Admiralty would require the return of 4” and 4.7” guns currently mounted for Coast defence for issue to new merchant ships. Eastern Command had four 4” guns mounted for coast defence including the two guns at Dunwich.
By August 1941, further Naval 6” equipments were available and a limited number of 15˚ 6” Land Service guns were expected to become available soon as they were replaced at major defended ports by 45˚ 6” equipments. Bawdsey in Suffolk was one site earmarked to receive two of the Naval guns (these were subsequently earmarked for Lowestoft (Grand Hotel) as Bawdsey was to receive two Naval guns from Foulness). Two batteries in Harwich (one of which was Landguard Right battery) were recommended to receive the new 45˚ 6” equipments sometime after October 1941 as production permitted.
By October 1941, the Prime Minster had ruled out any further increase in the number of personnel for Coast defence. This resulted in some planned batteries not being constructed although Grand Hotel battery, on which work had already started on, was to be completed. Other arrangements were also considered such as reducing the state of readiness at batteries other than Examination batteries and anti-motor torpedo boat batteries and placing some batteries on a care and maintenance basis. It was also planned to reduce the number of personnel at some batteries, selected in order of priority from the Army Commands as follows: (1) Western Command (2) Scottish Command (3) Northern Command (4) Southern Command – north coast (5) Southern Command – south coast and Eastern Command (6) South Eastern Command.
Despite the potential reduction in manpower, plans were still underway to modernize some batteries by replacing 15˚ 6” equipments with 45˚ 6” equipments and installing 35˚ 9.2” guns for a counter -bombardment role (i.e. to protect ports from attack from modern battleships and cruisers). The 45˚ 6” equipments were long range guns, with a maximum range of 24,000 yards, and were intended for the long range engagement of light cruisers, merchant ships etc in a counter-bombardment role as well as a (long range) close defence role. In a counter-bombardment role it was suggested batteries should consist of three 45˚ 6” guns but for a close defence role only they should consist of two guns.
Counter-bombardment 35 ˚9.2” batteries were also recommended to consist of three guns. With the use of spotter aircraft it was possible to engage enemy ships up to 40,000 yards with these guns. Without the use of spotter aircraft, a range of 26,000 yards was more realistic.
With regards to a counter-bombardment role, the assessment for Suffolk’s ports was:
(Yarmouth) and Lowestoft: Although important for mine sweeping and Coastal Force flotillas, they were not regarded as being important enough for the enemy to deploy capital ships in an attack against. Although it was of course possible that capital ships could attack these ports, the risk was considered so low that 9.2” equipments should not be employed. However, it was agreed to consider these ports for receiving some of the 45˚ 6” equipments.
Harwich: The Admiralty considered Harwich to be a port likely to be subject to bombardment. It was considered that the currently deployed 15˚ 9.2” equipments, with a range of 17,500 yards, were totally inadequate to defend Harwich against bombardment. A three gun 35˚ 9.2” battery had already been approved in August and this was considered to be adequate.
In the end, the only battery in Suffolk to be modernized was Landguard Right battery, which received two 45˚ 6” mountings (a third was planned but never installed), which gave the battery an additional role of Counter Bombardment. The new 9.2" equipments for Harwich were cancelled as a result of the implementation of the scheme to reduce the ceiling of manpower in Coast Artillery - "EBB-TIDE".
Home Forces Coast Defence Committee papers, TNA