Exploring Kent's Past

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Monument details

Summary

An underground Zero Station of around 1942, constructed for the Special Duties branch of the GHQ Auxiliary Units.

Monument Types

• (Former Type) AUXILIARY UNIT SPECIAL DUTIES ZERO STATION (1942, Undated)

Full description

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Summary
An underground Zero Station of around 1942, constructed for the Special Duties branch of the GHQ Auxiliary Units.
Reasons for Designation
The Hollingbourne Zero Station of around 1942, constructed for the Special Duties branch of the GHQ Auxiliary Units is scheduled for the following principal reasons:

* Historic importance: in 1940 the formation of the covert GHQ Auxiliary Units was given priority in response to the perceived threat of imminent German invasion. The few remaining Zero Stations are an important record of the evolving forms of clandestine warfare that were developed at that time;

* Period: although one of a considerable number of monuments characteristic of the Second World War, the Zero Station contains evidence of, and relates to, a secret and vitally important role in terms of national security; * Rarity: it is believed to be one of only 50 underground stations built in Britain during the Second World War, most of which were destroyed thereafter; * Survival: the structure of the station survives very well and some vestigial fittings survive including an element of the hatch opening mechanism, power switches, ventilation pipes and cabling; * Potential: it has significant potential to inform our understanding of how the Special Duties branch would have operated under invasion conditions, which will increase our knowledge of this relatively little understood area of C20 military history; * Documentation: surviving cartoons by Wireless Operator Rigby, which illustrate how the Zero Station operated and how it would have been evacuated in the event of discovery by the enemy, add to our understanding.
History
The Hollingbourne Zero Station was constructed as part of a secret military organisation, whose role was to operate in areas of Britain should they come under German occupation. With the increasing threat of a German invasion in the summer of 1940, the Prime Minister, Winston Churchill, directed that a covert Army unit called ‘GHQ Auxiliary Units’ be formed. The Operational Branch trained and equipped civilians to carry out acts of sabotage behind enemy lines. A separate branch called ‘Special Duties’, trained civilian volunteers living in the most threatened coastal areas of Britain to act as ‘observers’ and report on German military activities from within occupied areas. Observers would have left their reports in ‘dead letter drops’, which were delivered by runners to hidden wireless stations, called ‘OUT-Stations’. Civilian operators would then transmit the reports to military manned ‘IN-Stations’ (also known as Zero Stations) outside the occupied area. The wireless networks were set up by Royal Signals from the GHQ Auxiliary Units Signals. The Zero Stations were manned by specially selected signallers or by officers of the Auxiliary Territorial Service (ATS). Many of the Zero Stations were sited near to the Division or Corps HQs responsible for the operations in that area and reports were delivered to the nearby HQ by runner or telephone. Initially, Zero Stations were located in wooden huts near to the HQ which they served, but from 1941 onwards many were provided with concealed underground dugouts, as is the case at Hollingbourne. Alongside a Zero Station at Bilting and Tunbridge Wells, Hollingbourne controlled a network of around 13 'OUT' stations and reported into Canterbury or Sevenoaks control. The station at Hollingbourne appears to have been operational from 1942 until around July 1944. The first sites were located in Kent, Surrey and East Anglia but there was a steady expansion northwards up the east coast, eventually to Sutherland and Caithness. The network also expanded westwards along the south coast from Hampshire through Dorset, East Devon, Somerset and along the South Wales coast. Zero Stations were equipped with rations, water, basic sanitation and power supplies so that if the Germans occupied the surrounding area, they could remain concealed and operate in isolation for up to 21 days. Considerable ingenuity was used to conceal the entrances via trap doors and locking mechanisms. Special ventilation systems were built to provide fresh air in the dugout and to disperse foul air, generator exhaust fumes or cooking smells while muffling the sounds of activity and the noise of the generators. Aerials were concealed in nearby trees and the feeder cables were hidden under the bark. If access was gained into the dugout by the enemy, a layer of security was provided by heavy concealed doors, which gave time for the crew to destroy sensitive material and hopefully escape via a special tunnel with a hidden exit. At Hollingbourne, the small room at the bottom of the entrance shaft was designed to appear as if it were a standalone storeroom. The main chamber was hidden by a false wall with shelving. When a concealed catch was lifted, a section of the shelving moved out of the way, allowing the door to be opened. Along with the wireless equipment, the main chamber contained a small table with chairs, bunk beds and spare batteries with a generator to recharge them and a good supply of food. A third chamber (also concealed) contained the basic sanitary arrangements, ventilation plant and the entrance to the escape tunnel. Sketches by Miss Rigby, (see sources), who served at Hollingbourne, provide a humorous but chilling insight into the evacuation procedure for a Zero Station. Firstly, that no action was to be taken until the enemy were about to open the hatch. Once this had occurred the code word 'Scramble' would be transmitted three times. If the enemy discovered the hidden wireless room then all radio sets, valves and papers were to be destroyed. The detachment commander and the two operators would then quietly escape through the tunnel and attempt to kill the enemy, before joining up with the nearest British troops.
Details
An underground Zero Station of around 1942, constructed for the Special Duties branch of the GHQ Auxiliary Units. PRINCIPAL ELEMENTS: the monument is located within a long and narrow copse, centred on National Grid Reference TQ 86462 55524. It consists of an underground station designed for use by the Special Duties branch in the event of an invasion to monitor and report on enemy troops.

DESCRIPTION: the station is orientated north to south and is buried below ground. There is an access shaft to the north end and an emergency exit tunnel to the south end. It is subdivided into an entrance chamber, a room for sleeping and wireless operation, and a chamber for the access to the escape tunnel. It has the form of a buried Nissen hut, standing on a concrete slab. The principal structure is around 10.3m long and 3m wide, with curved corrugated iron sheets forming the walls and roof. It is subdivided by block partitions, which also support the walls and roof. A metal cover at ground level, provides access to a shaft. To the top there are metal stanchions for an earlier locking system. At the bottom of the shaft there is a small chamber, which has a circular ventilation aperture set into the corrugated wall. The dividing wall to the south has an opening (previously concealed during operations) of around 1.5m in height, allowing access to the central chamber which is the largest space within the station. It has vestigial, timber battens marking the operator positions and a vent pipe aperture to the south wall. Further south, an opening in the dividing wall connects to the northernmost chamber. This has two, 0.35m diameter, ceramic pipes, one positioned just off the floor and the other just below the roof. The dividing wall has a small fuse box and battens indicating the position of related equipment. The opposing wall has a ventilation aperture. The circular exit tunnel is around 1m in diameter and runs for around 5.5m, terminating in a square, concrete shaft which is visible from the surface. Towards the middle of the station and on the surface, there is a ventilation pipe concealed within the base of a tree.

EXTENT OF SCHEDULING: the station is concealed underground and there are no exclusions. The scheduled area covers the extent of the chamber and the escape tunnel. (1)

<1> Historic England, National Heritage List for England (Index). SKE29372.

Sources and further reading