World War II Tunnels at Porthcurno Telegraph Station

WORLD WAR II TUNNELS AT PORTHCURNO TELEGRAPH STATION

Underground wartime international communications centre built 1940–41 for Cable and Wireless. The structure consists of a pair of interconnected, rock-cut, concrete block-lined parallel tunnels cut into the hillside behind Eastern House, protected on the west by concrete blast walls. Ventilation vents built into these walls are the outlets for the internal air-conditioning system. Normal access was provided through two concrete block-lined passages leading to a pair of blast doors. An escape passage with flight of stairs leads to a protective concrete structure with further blast doors on the hillside to the east.

Within the tunnels there is a concrete block building with timber roof and planked ceiling. In the south tunnel, a small section of this building has been cut away and replaced with glass, allowing visitors to appreciate the construction details. Leading along the centre of the roof throughout the building is an air-conditioning duct with conical vents at frequent intervals. Hanging from the ceiling throughout most of the building are original light fittings. In the west part of the north tunnel is an emergency electricity generator, alternator and fuse panel manufactured by Lancashire Dynamo & Crypto Ltd. in 1941. Access to the space between the tunnel and building was provided by a ladder formed by rungs attached to the outer wall. A range of museum displays including original telegraphic instruments now occupies the tunnels.

Work started on 25 June 1940 and was carried out by Edward Nuttall and Co., major contractors for a number of important projects. The rock blasting caused considerable damage to neighbouring windows, and the material excavated was dumped to create a platform south of Eastern House. Inside the tunnels, a concrete block building was built to house the equipment, and on 31 May 1941 the tunnels were declared open by Lady Wilshaw, wife of the Chairman of Cable and Wireless, Sir Edward Wilshaw. Further protection was provided by a series of defences including barbed-wire entanglements, flood-lighting and flame throwers.

The telegraph station at Porthcurno had been established in 1870 when a cable from Carcavellos in Portugal arrived on the beach. This cable was the final link in a chain of cables leading from Bombay in India. During the whole of the 19th and early 20th centuries, Porthcurno developed into one of the most important international telegraph communications centres in the British Empire. By 1929, Porthcurno was accepted as the most important telegraph station in the British Empire, with 14 operational submarine cables terminating in a newly-built concrete cable hut situated close to the beach.

During World War II the importance and vulnerability of the telegraph station was recognised, and the whole operation moved underground in early May 1941 into a pair of tunnels blasted into the adjacent hillside. Between the end of the war and 1950 the telegraph station was refurbished, extended and opened as a training school. In 1970, exactly 100 years after the arrival of the first cable, the telegraph station closed although the training school remained until 1993. The site eventually transferred to the PK Trust who run Porthcurno Telegraph Museum.