Summary

A former Second World War Special Duties IN-Station located within the former grounds of Pinebanks, a late-C19 villa at Thorpe St Andrew, which was demolished in 2015. It is an underground structure, built to a standard plan by the Royal Engineers, and comprises a three-room operational area with an entrance shaft at the south end and an emergency escape tunnel and exit shaft at the north end. The site around the structure is now (2016) being developed for housing.

Source: Historic England

Details

PRINCIPAL ELEMENTS
A former Second World War Special Duties IN-Station located within the former grounds of Pinebanks, a late-C19 villa at Thorpe St Andrew, which was demolished in 2015. It is an underground structure, built to a standard plan by the Royal Engineers, and comprises a three-room operational area with an entrance shaft at the south end and an emergency escape tunnel and exit shaft at the north end. The site around the structure is now (2016) being developed for housing.

DESCRIPTION
The former Norwich IN-Station is an underground structure which runs in a north-south alignment for c 29.5m and has a maximum depth of 3m. At the south end is the entrance shaft which is capped with reinforced concrete and a thick layer of soil. It is c 0.9m square, constructed from breeze block, and descends to a depth of c 2.8m. Although the top two layers of walling were removed when it was capped in 1944, it still retains several rectangular niches on which the wooden frame supporting the hatch door sat. At the bottom of the shaft, where fragments of the frame and breeze block walling lie, there is a doorway in the north wall which provides access to a Nissen-type hut measuring c 6.47m long and c 2.83m wide. It is constructed from corrugated iron with a concrete paved floor and comprises three rooms separated by breeze block walls. The room immediately adjoining the entrance shaft is a small lobby or ante-chamber which was primarily used for storage. It measures 1.52m in length and has unpainted side and end walls. Its original 50 gallon water tank still stands in the north-west corner. Built against the centre of the north wall is a wooden shelving unit which conceals the plank and batten door to the wireless room behind. Although the removable shelves are now missing, it still retains the shelf brackets and the hidden locking mechanism which operated the door. The door itself has horizontal slots cut into it so that the shelves cut sit flush against. The opposite side of the door in the wireless room is covered with Union Cloth, a felt-like material impregnated with paraffin oil, which was designed to prevent the spread of toxic gases and exhaust fumes. The room is the largest of the three and measures c 3.43m in length. It has white painted side walls and whitewashed end walls while the floor retains small sections of brown linoleum. On the south-west wall there is the wooden backboard for an electrical switchboard from which the wiring for generator-fed and battery-fed lighting circuits still run. To the ceiling there are two light fittings. At the south end of the west wall there is an exit point for three aerial feeder cables, indicating that the position for the table housing the wireless sets was probably in the south-west corner. Two ventilation pipes with wooden stoppers are set within in the north-west wall; the inlet pipe set at floor level and the outlet pipe at roof level. A conduit for a cable runs all the way along the roof from the generator room, ending at what is believed to be the position of the main panel or switchboard in the south-east corner of the room. The message drop pipe also survives here. At the centre of the north wall two plank and batten doors placed back-to-back provided access to the generator room. Hand written in red crayon on one of the doors is the warning message 'DANGER - 250 VOLTS - KEEP OUT'. Both doors are fitted with Union cloth around their edges. The generator room is of an identical dimension to the lobby/ante-chamber, with white painted side walls and whitewashed end walls. To the north wall there are two ceramic ventilation pipes of which one is soot stained and was therefore probably used to extract the generator’s exhaust fumes. Running along the east side are the two ventilation pipes from the wireless room, both with rectangular ventilation openings cut into them. Beside the inlet pipe is an electrical panel (all wires now cut) with two 60cm lengths of power cable attached to it. On the wall above is a light fitting along with the wiring for a second fitting. An opening in the north wall leads to the escape tunnel which is about 17m long and constructed from 18 segments of concrete pipe, each about 90cm long and externally clad with sheet metal. The tunnel leads steadily upwards and curves in a north-easterly direction at roughly its mid-point before reaching the escape hatch. Along its length there are a number of clips for securing power cables (now missing) which suggest that the dugout was connected to mains power. The tunnel emerges into a man-hole like escape shaft lying close to the ground surface. It is c 0.9m square with breeze block walls and a concrete floor. Like the entrance shaft, although the top two rows of walling were removed to conceal the shaft when the station closed in 1944, it still retains several small rectangular niches that would have supported the wooden framework for a pulley system that operated the escape hatch trap door. The hatch is now covered by concrete slabs.

A tall pine tree standing adjacent to the west side of the structure still retains part of one of the aerial feeder cables and is subject to a Tree Preservation Order.

EXTENT OF SCHEDULED AREA: as the monument survives as a buried feature there is no physical surface representation of its existence save for the capped entrance and exit. Its extent is therefore more clearly defined on the accompanying map extract.

EXCLUSIONS: the modern tarmac surface above the monument is excluded from the scheduling but the ground beneath is included.

Source: Historic England

Reasons for Scheduling

The buried remains of Norwich IN-Station, a Second World War underground wireless station, Thorpe St Andrew, is scheduled for the following principal reasons:
* Historic interest: the perceived threat of imminent German invasion and occupation was so great in 1940 that the formation of the Auxiliary Units was given priority by Churchill, and secrecy was paramount for its potential success. By 1944, this threat was considered negligible; nevertheless, the continued value placed in a secure and secret communications network prior to the Normandy invasion is indicated by the construction of this IN-Station;
* Period: although one of a considerable number of monuments characteristic of the Second World War, it 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 32 IN-Stations which were operational in Britain during the Second World War;
* Survival: this site, along with all of those in the network, was stripped of equipment at the end of the Second World War. However, many original fixtures and fittings still survive and it is regarded as the most intact example of the 12 purpose-built IN-Stations whose whereabouts have been uncovered and investigated, physical remains of a policy of national interest for which there is little other evidence;
* Potential: as the most complete IN-Station known to survive it has significant potential to inform our understanding of how the Special Duties branch operated, or was perceived to operate under invasion conditions, which will increase our knowledge of this relatively little understood area of C20 military history;
* Documentation: due to the secret nature of the Auxiliary Unit organisations, very little documentation ever existed relating to them, and some information is thought to have been destroyed. However, since it was discovered in 2012, it has been widely written about and this information will greatly enhance our understanding of both the monument type and the wartime role of Auxiliary Units.

Source: Historic England

Sources

Books and journals
Simak, Evelyn, Pye, Adrian, Churchill's "Most Secret" Special Duties Branch, (2014), 127-130
Simak, E, Pye, A, Churchill's Secret Auxiliary Units in Norfolk and Suffolk, (2013), 171-183
Websites
Information on Norwich IN-Station from the Coleshill Auxillary Research Team website, accessed 25 February 2016 from http://www.coleshillhouse.com/specialdutiesbranch/norwich-special-duties-zero-station.php
Informaton on Norwich IN-Station form Norfolk Heritage Explorer, NHER Number 58128, accessed 25 February 2016 from http://www.heritage.norfolk.gov.uk/record-details?MNF64097-World-War-Two-Zero-Station&Index=55658

Source: Historic England