Churchill's British Resistance - The Special Duties Branch


Norwich Special Duties Zero Station - EXCLUSIVE CART REPORT

This page was last updated at 9:04am on 7/6/12


Thank you for selecting information on the Norwich Special Duties Zero Station in Norfolk. The info and images below have been supplied by Aux researchers Evelyn Simak and Adrian Pye.

Norwich Zero-station – call sign “Bowling Zero”

Like all other known Zero-stations, it was constructed to a standard plan by units of the Royal Engineers who would have been unaware of its intended use. Situated on high ground, possibly on the highest ground in the wider vicinity, the location was obviously carefully chosen. Furthermore, there was also a good choice of tall trees in the immediate vicinity. Tall trees with at least one strong horizontal branch pointing in the right direction - towards one of the Zero station’s outstations – were required for the placement of the aerial/s. Many of these trees were damaged and consequently felled after the 1987 gales. The Zero station would have been used for practice runs and for going to ground in the event of an evasion only. Everyday work was done in an above-ground Control station - commonly disguised as a Met hut - which would have been located nearby. These huts were commonly removed after stand-down but the concrete base they were built on occasionally still marks the location.

The Zero-station’s call sign was “Bowling Zero” - interestingly, the site is located beside a Bowling Green. It received broadcasts from outstations based at Edingthorpe, North Creake, Aldborough (sub-outstation), Southrepps (near Cromer), Aylsham (The Beeches, Pound Road – now Holman Road), Wroxham (closed in 1943 when the AU Scout Section that ran it was stood down; their call sign was Bowling 9), in the Horning-Ludham area, and one other as yet to be found outstation (possibly in the vicinity of Fritton near the Norfolk/Suffolk border). Outstations or sub-outstations are believed to also have been in the villages of Brampton near Aylsham and Brandiston in the Cawston-Booton area, both in North Norfolk.
Regarding its layout and contents, the structure is an almost identical clone of other known zero stations as indeed they were all built to the same specifications by units of the Royal Engineers.


Norwich Zero-station is located on private property in Thorpe St Andrew.


In the 1940s, the property was occupied by Mrs Jarrold whose son John was a keen radio ham who built his own radio sets – one of which believed to have been situated in one of the rooms at the top of a nearby tower. Although we failed to find any evidence, we firmly believe that John is the key link and that he would have been actively involved. He certainly kept quiet about whatever it was that he was doing because when we told his son about the existence of a top-secret underground radio station in his grandparents’ garden he at first outright refused to believe us.

Frank Hewitt - an Auxiliary Units (Signals) Corporal who, together with a small team was in charge of servicing SD radio stations all over the UK - recalls that in 1942 “I spent a short time in Norwich, being taught the rudiments of the special (radio) set by some ATS officers at the top of some tower in the grounds of some big house.” This clearly implies that not only was the set ‘special’ (and hence certainly not one of Mr Jarrold’s own radios) but rather that this was the set used by the Control station which was situated here.

In the 1940s, the gardener employed by the family (Mr Godbolt) witnessed the construction of an underground chamber. The digging up of the family’s tennis court is remembered by one of Mr Jarrold’s sons, then a young boy. He never managed to find out why this had been done. As the Zero-station is situated where the tennis court used to be it is probably safe to assume that it was dug up on the occasion of the Zero-station’s construction. Mr Godbolt recalled that he had to sign the Official Secrets Act, and he never mentioned what he had witnessed until after his retirement, when he shared his secret with a young grounds man. He did, however, not reveal the location.

In the spring of 2012, we were contacted through CART by a retired grounds man who informed us about the existence of a secret WWII ‘bunker’ and a meeting was arranged within the same week.

Action taken

Armed with spades, shovels, a crow bar, and a metal detector we met the owners’ development manager at the site. What we found left us quite breathless (in more than one way) – see Description.

The property owners acted swiftly and with great responsibility in that the in-house surveyors as well as Norfolk County archaeologists were informed within hours. Furthermore, thanks to the owners’ generosity and trust we were the first to carry out a detailed survey before anyone else came on site, and for this we are immensely grateful. Bound by our promise not to talk about what we had seen, we quietly continued our research and we produced a report to be used for guidance by all concerned - knowing that nobody would be familiar with what they would be seeing, and that for this reason not only would many small details go unnoticed but, more importantly, the importance of this find might not be fully understood. Nowhere in the UK was there another Zero-station in a similar state of preservation and with so many original features still in place. Consequently, we suggested that the structure is of national importance and that it should for this reason be preserved in its entirety.
In due course, the Norfolk County archaeologists requested our presence when conducting their own assessment - needless to say that we were very pleased to be invited to meet them. To our great delight, they unanimously decided on the spot to involve National Heritage, resulting in the Zero station being declared a Scheduled Monument of national importance. Our report (below) now forms part of the archaeological survey of the site.


We found three concrete slabs (not original), covered by a layer of about 20 cm of soil laid over a small opening, which we established to have been the exit opening. The original cover was described to us as having been made from rough reinforced concrete which was poured onto wooden boards laid across the opening. Only concrete rubble remains. Below the cover, a concrete culvert pipe emerges into a manhole-like space with breezeblock walls. Mention has also been made of a few steps leading down to the bottom, however, no trace remains of said steps, and no trace of steps was found during the excavation of the exit shaft. The top two rows of breezeblocks appear to have been knocked off in order to lower the shaft for better concealment when the Zero-station was closed in 1944. The top row of the breezeblocks would originally have been capped by an approximately 3 cm thick layer of concrete to stop rainwater from trickling down. The breezeblock and concrete rubble was thrown down the shaft. In the current top row of breezeblocks there are several small rectangular recesses which once would have carried a sturdy wooden frame supporting a number of pulleys. A steel hook tied to a length of twisted steel wire at the bottom of this manhole was found in 1988, along with a 0.65m long steel pipe and a C-bracket.

Excavation of the exit shaft has brought to light altogether 5 small pulleys; several lengths of aerial feeder cable that appear to have been dumped here; a brass door catch (presumably for the exit hatch) and what appears to be a door handle; two shards of a glazed ceramic ventilation pipe, an ‘S’-shaped hook with a length of steel wire wrapped around it; two long (1.55m) and one short (0.65m) steel pipes, two C-brackets and numerous rusty nails. The floor of the exit shaft is of concrete that was covered with a layer of bitumen for waterproofing. There are two rectangular openings in the floor, one containing seven cast iron sash weights of various lengths, bundled together with steel wires, acting as the counterweight of the exit hatch.

Rackheath Hall SDS Zero Station 2  Rackheath Hall SDS Zero Station 3

Similar to a drawing (see Fig 4 below) found in a document believed to have come from Coleshill and dating from the 1940s, giving instructions for the building of trapdoors, the Zero-station’s exit hatch probably consisted of wooden boards or of a plywood sheet, nailed onto two lengths of 2 x 3 inch timber. The door would have been attached to the two aforementioned metal pipes - threaded through wooden battens for support and then through the boards - and fixed in place by a nut at each end. The length of these pipes indicates the original height of the drop-down shaft which would have been about 1.60m. Each one of these pipes was contained within a shorter length of (slightly wider) pipe that was affixed to a wooden frame with two C-brackets. In all probability the trapdoor mechanism would have been activated by pulling a wire. We presume that the counterweight rested on a hinged board, secured by a catch. Pulling the wire released the catch, the board dropped out from under the counterweight, and the counterweight in turn started to descend downwards until it had reached the bottom of the opening in the floor. Simultaneously, the two long pipes, held within the shorter pipe sections, were pushed upwards, resulting in the trapdoor being gradually raised horizontally above ground level. The small opening created by this action would have been just large enough to squeeze through and escape (see Fig 3). Above ground the trapdoor would have been hidden under a layer of soil. In the event of discovery, the Zero-station would never have been used again and the emergency exit mechanism was hence intended to be used only once. ATS personnel were not usually issued with firearms that could have been used for defending themselves, they were, however, instructed to destroy the radio sets before attempting a get-away.

Rackheath Hall SDS Zero Station 4  Rackheath Hall SDS Zero Station 5 

The escape tunnel is 17 metres long. It was constructed by aligning 18 segments of concrete culvert pipe, each measuring about 90 centimetres. The tunnel leads steadily downwards, curving in south-westerly direction about halfway down. The concrete pipes have an exterior lining of sheet metal, presumably to keep out dampness. This lining can be seen through the gaps created by the curve of the tunnel.

Rackheath Hall SDS Zero Station 6  Rackheath Hall SDS Zero Station 7

There is evidence of the existence of two 240V power cables, running parallel to each other along the whole length of the tunnel. The cables were held in place, about half-way up the right hand side, by double cable clips, fixed in place by nails that were hammered into crude wooden plugs wedged into the gaps between two pipe sections. Some of these plugs are still in place as are a number of cable clips, some lying on the tunnel floor. The existence of at least one such cable is confirmed by Mr G who actually pulled a 6-metre length out of the tunnel. Two cables of similar type were found at Hollingbourne Zero-station in Kent but what purpose they might have served has as yet to be established.

The tunnel emerges in a buried Nissan-type hut chamber (also often referred to as “elephant shelter”) consisting of three rooms which are separated by 23 cm (9 inch) thick breezeblock walls. The rooms were accessed through wooden doors which are still in place, functional and in good condition. As the entrance opening remains sealed the only way in at present is through the emergency exit tunnel. The following description of the rooms follows the order in which they were first encountered - the last room (generator room) first and the entrance shaft last.

The room immediately adjoining the escape tunnel is the generator room. Looking towards the tunnel opening, evidence can be seen that the tunnel used to also be secured at this end, where it emerges into the generator room. The cover appears to have been made from wooden boards and some of the screws fixing it to the wall are still in place, embedded in the surrounding breezeblocks. Only two boards of this cover remain – both are of similar size and have one straight and one rounded edge, with the latter fitting snugly into the rounded opening of the culvert piping. One of these boards was found hidden in one of the two concrete vent pipes, the other on the floor of the ante-chamber by the entrance shaft. In all likelihood this room would have been used for housing a small generator and for storing the batteries powering the lighting as well as the TRD radio sets. The generator would have been used for the re-charging of said batteries and for providing back-up in case of an emergency. The whitewashed wall above one of the two small glazed ceramic vent pipes in the breezeblock end wall appears to be soot-stained, indicating that it could have been used for extracting the generator’s exhaust fumes. A second, similar pipe is set into the end wall above the tunnel opening. The other end of this pipe can be glimpsed through a recess near the top of the exit shaft’s wall, indicating that at this point the pipe is actually situated within a breezeblock. The corrugated sheeting in this room was painted off-white; the floor is covered with paving stones. A fire bucket - a sand-filled fuel or food container with an improvised wooden handle - stands by the wall beside the twin doors leading into the radio room.

Rackheath Hall SDS Zero Station 8Rackheath Hall SDS Zero Station 9

On the left hand side (looking towards the exit tunnel) the generator room is traversed by two large concrete ventilation pipes, one near the bottom (the inlet pipe) and one near the roof (the outlet pipe). Both of these pipes have a small rectangular cut-out which provided ventilation in the generator room. The joint of the bottom pipe is supported by a piece of breezeblock. Beside the inlet pipe, right next to the tunnel opening, there is an electrical panel, albeit with all wires cut. Two approx. 60 cm lengths of power cable are still attached to it. The insulation at the ends of the two cables has been stripped and the two strands of twisted steel wire were pulled apart, in all likelihood to be clipped onto the protruding poles of the lead-acid batteries that powered the lighting as well as the radio sets. A pair of light fittings (one missing) is on the wall above. Interestingly, the course of this section of conduit as well as the position of the two light fittings can also be seen outlined on the wall in red chalk, no doubt by the Royal Engineer who installed it.

Rackheath Hall SDS Zero Station 10Rackheath Hall SDS Zero Station 11 

Even without much knowledge of electrics, one glance at the panels indicates that appliances other than two radio sets and presumably two lighting circuits would also have been controlled from here, but what exactly these other devices would have been remains a mystery which left our military electronics engineer friend - who had expected to find no more than 6 wires, instead of 11 - quite baffled:

“Panel A (beside the entrance into the radio room) is the most complex in that it housed the light switches as well as other things. Close examination shows circular marks from what appears to have been switches. I was not expecting to see more than six wires but on this panel there are 13 – probably 5 pairs and a group of 3. I have no idea why so many. Another panel (panel B) was expected on the opposite wall but there is only a pair of wires. Panel C (in generator room) has 11 wires, again more than expected. Panel D (beside exit tunnel) is clearly the battery termination panel with a connecting block. It appeared to me that the two 6V batteries were used to power two separate circuits. This would make sense if the lights were on one and the radios on the other. The lights are clearly in pairs and it is also clear that one side of the pairs has a different type of wire and this could be because each pair consisted of one 6V 6W bulb while the other had a mains powered bulb. This is just a guess at the moment.”

A small, simple and obviously homemade collapsible screen (measuring about 0.40 x 0.70 cm when intact), constructed from sections of oil-soaked black-out fabric (it looks like a blend of felt and Hessian) and interspersed by six or seven lengths of wood, was found lying on the floor beside the tunnel opening. It used to be attached to a piece of wood that is wedged into the small space between the outlet pipe and the roof, from where it had dropped off when the fabric holding it together deteriorated. A markedly darker area to both sides of the rectangular cut-out in said pipe indicates that this screen would have been draped around here, blocking the opening. We have so far failed to find a plausible explanation as to why this would have been necessary. A very similar set-up was found at Heiferlaw Zero-station > and also at Shipley Zero-station > where the cut-out was covered by what appears to have been a wooden board. A small pile of ash that appears to have originated from burnt paper can be seen through the rectangular cut-out in the inlet pipe – perhaps the remains of code sheets that were burnt when the Zero-station was closed?

Rackheath Hall SDS Zero Station 12  Rackheath Hall SDS Zero Station 13

The radio room is separated from the generator room by twin doors - two sturdy wooden doors with a raised threshold in-between. The doors are intact, fully functional and complete, including hinges, handles and catches. It is interesting to note, however, that the Norfolk-barn-door type catch was replaced by a much stronger one on the inner door. Both doors have a thick black textile fabric affixed all the way around their outer rims, albeit only on the sides that face each other when both are closed. We believe that this fabric, which appears to have been soaked in oil, served several purposes, depending on where it was used: to stop light penetrating through (entrance door); for protection from poison gas; for sealing the twin doors in order to prevent generator exhaust fumes from penetrating into the radio room (twin doors at exit); and for sealing the cut-out in the outlet pipe (in generator room) for reasons not yet fully understood. There are two thumb-sized holes at one end of the door lintel and there is also cable clip just below, which indicates that two cables were fed through these holes. What type of cables they were and purpose they might have served we do no know. On the whitewashed wall beside it, three straight vertical lines can be seen drawn with a pencil at equal distances, and there are also three wooden plugs in the cement seam between two rows of breezeblocks - indicating that a small shelf was once affixed here. If so, no trace of it remains.

Rackheath Hall SDS Zero Station 14 Rackheath Hall SDS Zero Station 15

The two aforementioned concrete ventilation pipes, the inlet and the outlet pipe (traversing the generator room) emerge in the radio room, to the left of the twin doors (viewed from the entrance doorway). Their homemade wooden plugs (in all probability used for noise and generator exhaust fume reduction) are in situ. In the radio room the cable conduit runs all the way along the roof, terminating at what we believe was the main panel or switchboard on the opposite wall, beside the entrance doorway. Once again, the set-up of the wiring is confusing and all the switches were removed.

Rackheath Hall SDS Zero Station 16 Rackheath Hall SDS Zero Station 17

Rackheath Hall SDS Zero Station 18 Rackheath Hall SDS Zero Station 19

The floor of the radio room is covered with precisely laid concrete paving slabs which in turn were covered by a layer of brown linoleum, small sections of which are still in place - some bearing the indents of objects that once stood on them. The breezeblock end walls are whitewashed and the corrugated sheeting is painted off-white. Three aerial feeder cables disappear through the wall at about 40 cm above floor level near the right-hand corner (near the entrance doorway). The presence of three feeder cables indicates that there were three aerials – with possibly, but not necessarily each one running up a separate tree. The table for the radio sets would have stood near this corner in the vicinity of the aerial feeder cables and the main switchboard.

Rackheath Hall SDS Zero Station 20  Rackheath Hall SDS Zero Station 21

Above ground, part of one of the aerial feeder cables can still be seen high up on a pine tree, situated about 5 to 10 metres from where the duct enters the radio room through the west wall. The tree (Pinus silvestris) has the conservation number 0723 and cannot be felled. The length of feeder cable will therefore be safe for as long as it takes for the wind to take it down.

An in-depth description of the organisation and of the radio sets used, written by Arthur Gabbitas, is published under the heading of “Auxiliary Units Signals” at David Waller’s website: Mr Gabbitas (d 1999) was a former Royal Signals Corps corporal who served with the Auxiliary Units and travelled the country to service the various Zero, Control and outstations. Cpl Frank Hewitt (mentioned above) was a friend and best man at his wedding. The following is an excerpt:

“The wireless set used was code-named TRD. It was housed in a metal case measuring about 0.40 x 0.24 x 0.23 cm and powered by a large conventional 6-volt 85 A.H. accumulator battery, the voltage of which was boosted to 240V by a vibrator contained within the set. The frequency used ranged from 48 to 65 mcs, nowadays commonly used by BBC1 TV. The aerial terminals were connected inside via a piece of flat twin feeder and to a 72-ohm flat twin feeder outside the front panel, leading to the dipole antenna hidden in a tree.”

Back inside the radio room: the presence of different types of wires (orange at left, mauve at right) indicates that there would have been two lighting circuits - one AC circuit probably at 250V, derived from the Chorehorse generator or similar, and another, totally separate circuit for silent, battery-powered running at 6V just as the radios did. Two pairs of light fittings are in the radio room (on ceiling) and a similar pair is in the generator room (on wall). Remains of tiny 6V 6W “Sunshine” light bulbs with bayonet fittings were found lying on the floor in a corner. From this we can safely assume that the lighting conditions would have been very poor indeed.

Rackheath Hall SDS Zero Station 22  Rackheath Hall SDS Zero Station 23

We had read about the existence in Zero-stations of a hidden door leading from the ante-chamber by the entrance into the radio room, and also that for anybody not in the know the ante-chamber would have had the appearance of a small storage room, giving no clue as to what lay hidden behind the wall. At Norwich Zero-station, the interior (radio room) side of this door is covered entirely with the already mentioned sticky black textile fabric, large sections of which are still in place, albeit in shreds.

Rackheath Hall SDS Zero Station 24 Rackheath Hall SDS Zero Station 25

The other side of this door, however, appears to be something different entirely. Coming down the entrance shaft, the uninitiated would have found themselves in a small room that to all intents and purposes was used for storage, with a small water tank standing against the wall on one side. On the wall facing the entrance shaft they would have seen a storage shelf, stacked with boxes and tins and perhaps a few boxes of ammunition. This shelf is designed to look like a bookcase, with a frame extending to both sides of the doorframe (overlapping it) and also to above the door up to a height of 1.65m. The wooden brackets which would have supported the removable shelves are still in place and the door itself has small cut-outs so that the shelves fitted partially into it, perfectly concealing both the door and the door frame when the shelves were in place and the door closed. The shelf boards are missing but the bookcase-style frame is in situ – and it is the one only known to be still in existence.

Rackheath Hall SDS Zero Station 26 

Rackheath Hall SDS Zero Station 27


The section extending to above the door lintel has two lengths of wood affixed to the panels covering the wall. These lengths of wood, one on each side, appear to be fixed in place by two screws, one at each end. The one on the right hand side, however, is held by only the top screw. The bottom ‘screw’ is actually a nail. This piece can be moved sideways and in doing so it reveals a small carved out recess and a hole drilled through it. The hole is just large enough to allow for a piece of string to pass through. The other end of this string is still tied to the door catch (on the radio room side), which could be released by pulling said string, and the radio room could then be entered by swinging forwards the door - but not without first removing at least some of the shelves. Standing in the door, the last person to enter the radio room would have replaced the shelves and the items stored on them. On closing the door it would once again have been invisible to anyone from outside.

Rackheath Hall SDS Zero Station 28  Rackheath Hall SDS Zero Station 29

The ante-chamber by the entrance shaft still houses a 50-gallon water tank, covered with a piece of sheet metal. The tank is still ¾ full of water and rests on four concrete plinths. Beside it there are two fire buckets, old fuel or food containers with improvised wooden handles, filled with sand. The walls of the entrance shaft, the breezeblock end wall of the ante-chamber and the corrugated sheeting in this room were not painted. The floor is covered with concrete paving slabs. The room does not contain any other items, but a chemical toilet (Elsan) would in all likelihood once have stood by the wall opposite the water tank, hidden behind a curtain.

The drop down entrance-shaft faces the secret doorway into the radio room. A wooden or steel ladder would once have been used for access. A large heap of concrete rubble is lying at the shaft’s floor. Presumably this rubble was created when the top of the shaft was lowered by removing the top layers of breezeblocks, in order to hide its presence when the opening was sealed up after stand-down. Affixed to the wall to the left of the entrance shaft (seen from the radio room) there is a cast iron pipe which ends at about 50 cm above floor level. Civilian informants might have used it to drop off their messages here, concealed in split tennis balls, to be read and then forwarded to headquarters by ATS personnel. Other sources have suggested that the pipe was used for ventilation purposes, and indeed the pipe would have been the only source of ventilation in the ante-chamber. It is possible that it served both purposes.

Rackheath Hall SDS Zero Station 30  Rackheath Hall SDS Zero Station 31

A number of lead counterweights (16 cm diameter, 2 cm high approximately), each with a hexagonal opening at its centre and still held together by a length of twisted wire, were found buried under the rubble at the bottom of the entrance shaft. As both the size and the quantity of the counterweights would have been defined by the finished weight of the trapdoor, the weights in all likelihood would have been made on site: a roughly saucer-shaped scoop would have been made in the sand and a bolt stood upright in its centre before molten lead was poured into the depression. When set, the bolt was knocked out and the process repeated until there were enough weights to counter-balance the trapdoor. The weights would once have been attached to the pulley system that was used for operating the opening mechanism of the entrance hatch. 

Rackheath Hall SDS Zero Station 32    Rackheath Hall SDS Zero Station 33

Viewed from below, the entrance opening is covered over with wooden boards. Almost at the current top of the breezeblock wall there are several small rectangular recesses.  They held the wooden frame that surrounded the opening and probably supported the entrance hatch.  A small pulley still adheres to a section of badly deteriorated wooden frame (it has since come down).  Two more pulleys were found amongst the rubble below.  The pulleys formed part of the opening mechanism that operated the concealed hatch.  Remains of sticky black, oiled fabric are still adhering to the wall above the roofline of the corrugated iron shelter.

Rackheath Hall SDS Zero Station 34

Finding the exact location of the entrance from above ground was difficult and it took some plotting and planning as well as shouting and banging on the roof before the exact spot could be found and excavated. The entrance was sealed by laying wooden boards across the opening and then pouring rough concrete, reinforced by lengths of (probably waste) metal rods and what appears to be a section of gas pipe, on top of it. The concrete cap is covered by an approximately 40 cm thick layer of soil. 


Fig 1:  Bookcase-style storage shelf concealing entrance door

Rackheath Hall SDS Zero Station 35

Fig 2: Fingerprint in linseed oil putty, left by the Royal Engineer sapper who installed the wiring

Rackheath Hall SDS Zero Station 36

Fig 3: Plan drawing of Zero-station, viewed from above and from the side

Rackheath Hall SDS Zero Station 37

Fig 4: Instruction for building trapdoors (Coleshill course, 1940s) depicting the type of trapdoor used at the exit opening.

Fig 5: Wiring diagram

Rackheath Hall SDS Zero Station 38


Overall length from entrance to exit incl tunnel: 85ft = 26 metres
Thickness of end walls: 23 cm/ 9in. Material: breezeblocks
Roof height: 2.10m (6ft 10 inches)
Entrance shaft: 0.90 x 0.90m / 3 x 3ft – 2.80 m (9ft) high from floor to covering boards
Dimensions of ante-chamber room: 1.50 x 2.85m (5 ft x 9ft 4inches) on floor. Paving stones on floor. Walls unpainted
Water tank: 0.76 wide x 0,55 x 0.55m - ¾ quarters full of water – sheet metal cover– tap in working order
Concealed door: 1.35 x 0.81m – doorstep 4 cm high. Back blacked-out
Bookcase-shelf: 17 (outer frame) x 24 x 14 (inner frame) cm deep
Shelf: 14 cm deep x 1.24 m long, 3 cm thick board. Height: 1.65m
Dimensions of piece of wood that conceals door catch mechanism: 22.5 x 5 x 3 cm
Radio room: 3.50 x 2.85m (11ft 3inches x 9ft 4inches) measurements taken on floor
Large inlet/outlet pipes: concrete; both 23 cm (9 in) internal diameter
Floor in radio room: Paving stones, covered with linoleum. Breezeblock end walls whitewashed, corrugated steel wall off-white
Exit doorways: 1.50 x 0.93 m – doorstep 78 cm wide by 11 cm high. Black-out fabric around inner edges
Generator room: 1.50 x 2.85m (5ft x 9ft 4inches) measurements taken on floor. Paving stones on floor, walls painted
2 small glazed ceramic vent pipes, one above tunnel (10 cm), one opposite twin doors (8 cm) - wall above soot-stained
Exit tunnel: 18 3-foot sections of concrete pipe, 55 ft long = not quite 17 metres with exterior lining of sheet metal
Exit opening: 1.20 (H) x 0.95 (W) x 0.70. 1 openings in concrete floor: 28 x 34 cm; 21 x 24 cm for counterweights

Exit hatch mechanism:
2 steel pipes 1.55m long; 2 nuts each at threaded end, spaced 7 cm apart; wooden plug in other end; 2 cm internal diameter;
1 steel pipe 0.65m long, 3.5cm internal diameter (its twin plus one C bracket is kept by Mr G)
5 pulleys
2 C-brackets (a third kept by Mr G)
Counterweight at exit (a bundle of 7 sash weights) – weight 25 kg (55 lbs)
Counterweight at entrance (4 lead weights tied together) – weight 13.6 kg (30 lbs)

Rackheath Hall - Auxiliary Units Signals / ATS Regional Headquarters (1940 – 1944)

Rackheath Hall

Rackheath Hall is believed to have housed SDS (Auxiliary Units Signals) regional headquarters from 1940 until presumably 1944. This might explain why on radio networks location lists the associated Zero-station appears under Rackheath. A map, hand-annotated in the 1990s by Arthur Gabbitas - an Auxiliary Units (Signals) corporal who was involved in the set up of Zero, Control and outstations - also gives the location at Rackheath. It is possible that a Control station might for some time at least have been in Fir Covert, a private woodland in the grounds of and just south of the Hall, perhaps before the Zero-station was built.

David Lampe (The Last Ditch); John Warwicker (With Britain in Mortal Danger; Churchill’s Underground Army); Arthur Gabbitas on David Waller’s Aux Units News website; Frank Hewitt (pers comm.); Stephen Lewins (CART CIO Northumberland); Will Ward CART CIO Dorset; Brian and Bob from Surrey;

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