Prior to the outbreak of war, the Home Ports Defence Committee produced recommendations for the safeguarding of Vulnerable Points during times of peace and war. A list of Vulnerable Points was provided to the Committee by the War Office and Admiralty, which were then classified as follows:
Places of Importance to be protected by the Government (Government factories, stores and magazines, explosive factories of importance, Naval oil and petrol stores, Wireless Telegraph Stations, Cable Landing Stations, Royal dockyards and torpedo factories).
Places to be protected by the relevant firm (shipbuilding yards, steel and iron works, firms supplying Royal dockyards, factories manufacturing war supplies, collieries producing coal suitable for Admiralty purposes).
Places of less importance to be protected by the Government (other Government factories, Naval centres, Port War Signal Stations and War Signal Stations).
On the outbreak of war, guards were not strictly provided in accordance with these recommendations and to try and reduce unnecessary expense and ensure military guards were provided in accordance with a definite policy, further memorandums were issued by the Army Council in August 1915. The policy specified that military guards were solely for the protection against attempts of damage or destruction on the outside by enemy agents. The responsibility to take measures to prevent damage caused by agents, who had managed to get access into a factory, either under false pretences, or employees sympathetic to the enemy or carelessness, lay with the factory owners. As a principal, factories engaged on producing explosives on a large scale for the Navy or Army were to be provided with a military guard.
A further Army Council committee recommended a classification of Vulnerable Points and that the principal of providing military guards to factories producing explosives for the Navy or Army on a large scale should be adopted for all Vulnerable Points, the damage of which could have serious consequences for the national defence or interest. Vulnerable Points were classified in accordance with the effect damage would have on the national defence or interest:
Class A – the loss or destruction of the Vulnerable Point would have a dominating influence on the conduct of the war.
Class B – the loss or destruction of the Vulnerable Point would have a serious influence on the conduct of the war.
Class C – Vulnerable Points of less importance of those in Class A or B.
The protection of Class A Vulnerable Points (including any external source of light or power) was of the first importance. It was recognised that because of the number of Class A Vulnerable Points it would be impossible to guard all those in Class B and C.
The nature of external attack and the principals for protection were specified as follows:
The whole of England, Wales and Scotland was deemed open to attack from Zeppelins. The whole area within 30 miles of the East Coast was open to attack by seaplane. Other areas were potentially under threat from seaplanes launched from carriers but this was considered unlikely. The whole area within 240 miles from Enemy occupied territory was open to attack by other types of aircraft. Measures were to be put in place to warn selected Vulnerable Points of impending air raids. Such Vulnerable Points were not permitted to have lights which show to sea or sky and all lights were to be screened or extinguished on the approach of aircraft. A policy of dispersal for construction and storage was recommended, so that it was not concentrated in one locality. Certain Vulnerable Points were provided with fixed anti-aircraft defences but as a general policy it was realised that it was just impossible to protect every Vulnerable Point with such defences.
Attack by enemy organized forces
This was not dealt with by the various committees on Vulnerable Points.
External attack by enemy agents
Every Vulnerable Point could be potentially attacked by enemy agents. Those requiring protection were to be protected by a fence and military guard.
Internal attacks by enemy agents
Protection was the factory / business owners’ responsibility. For large sites, the assistance of the police could be expected. The general principals that factories were to adopt to protect against internal damage by enemy agents or evil-disposed workers were:
Full enquiries to be made about new applicants, including liaison with the county police and labour exchanges.
Foreman should get to know employees, keep them under observation and immediately report any suspicions.
Entrances and exits to factories to be kept to a minimum and all workers to be carefully scrutinised by responsible persons on entering the factory.
All administrators and executive staff should have passes. Visitors should be escorted to the factory office and issued with a pass. Anyone challenged without a pass or one that had been tampered with was to be held for further investigations. Anyone with a foraged or falsified pass or without passes was to be proceeded against under the Defence of the Realm Regulations.
All buildings to be locked when not in use.
Vulnerable Points should be patrolled regularly by police or uniformed watchmen.
A proper system for dealing promptly with fire should be in place.
Attack by bombardment from enemy warships
Any Vulnerable Point within range of enemy warship or submarine guns was liable to attack.
Vulnerable Points in Suffolk, September 1915
Wireless Telegraph Stations:
Lowestoft (Naval, special), open to naval and air attack – provided with military guard
Ipswich (Naval, M.P.), open to naval and air attack – provided with military guard
Felixstowe, open to naval and air attack – provided with military guard, fixed anti-aircraft defences and defence against naval attack.
Ipswich (Docks for submarines), open to naval and air attack – provided with military guard
Cable Laying Stations:
Benacre (cable to Holland), open to naval and air attack – provided with military guard
Lowestoft (cable to Norderney, Holland etc), open to naval and air attack – provided with military guard
Wireless Telegraph Stations:
Lowestoft (Auxiliary Patrol, located on Pier, and Naval B and X stations), open to naval and air attack – provided with military guard
Felixstowe (Naval, destroyer), open to naval and air attack – provided with military guard and fixed anti-aircraft defences
Port War Signal Station:
Landguard (located in Fort), open to naval and air attack – provided with military guard and fixed anti-aircraft defences
Harwich (small Admiralty floating dock), open to naval and air attack – provided with fixed anti-aircraft defences
Coal and Oil Stores:
Felixstowe (oil reserves located in docks), open to naval and air attack – provided with military guard and fixed anti-aircraft defences
Ipswich (Ransoms, Sims & Jeffries – shell production), open to naval and air attack
Lowestoft (Oulton Road Living Bridge), open to naval and air attack – provided with military guard
Cable Landing stations:
Aldeburgh (cable to Shipwash Light Vessel), open to naval and air attack
Landguard Point (cable to Sunk and Longsand Light Vessels), open to naval and air attack – provided with fixed anti-aircraft defence
War Signal Stations:
Lowestoft, open to naval and air attack
Aldeburgh, open to naval and air attack – provided with fixed anti-aircraft defences
Covehithe, open to naval and air attack
Southwold, open to naval and air attack
Aldeburgh, open to naval and air attack
Lowestoft, open to naval and air attack
Felixstowe (wet docks), open to naval and air attack – provided with military guard and fixed anti-aircraft defences