Former RAF Ringstead Chain Home radar station, Osmington, Dorset

Summary

The structural remains of RAF Ringstead Chain Home Radar Station (AMES12B), built in 1941. It later served as Rotor station site ‘SRD’, and from 1963-1974 as a USAF Troposcatter Scatter station.

Chain Home was a ring of early warning radar stations built around the coastline as part of Second World War defences. The site includes two transmitter blocks, two receiver blocks, the bases of two receiver towers, a substation and a Standby Set House. They are dispersed over an area of some 26ha.

Description

A former radar station, built 1941 and refitted in 1952 and 1963, ceasing operation in 1974. The principal surviving features of the site include two transmitter blocks, two receiver blocks, two receiver tower bases, a substation, and a standby set house.

DESCRIPTION:
The two RECEIVER TOWERS, which were wooden, self-supporting 240 foot (73.15m) towers have been demolished. The four tapering, concrete foundation blocks or feet appear to remain in situ and mark the position of the two towers (at NGR SY7438381450 and SY7457581505). At the centre, between each of the four blocks would be a cable junction box with four brick or concrete corner piers and a concrete cap.

The two Type C RECEIVER (Rx) BLOCKS (at NGR SY7438781638 and SY7461281682) are rectangular structures built of reinforced concrete and surrounded by an oval earth mound or traverse for blast protection, measuring approximately 18m east-west and 25m north-south. Each receiver block has entrances to the east and south elevations with concrete blast or wing walls. The west Rx block has a brick blast wall to the south entrance and the east entrance is sealed with a modern timber door. There is a room with a plain timber architrave and no door to the right. A concrete ventilator protrudes from the roof. The interior is divided into a number of rooms and the original colour scheme of yellow and green paint survives along with lighting, other electrical fittings and a number of simple wooden architraves. The layout for both Rx blocks generally followed a standardised form (built to Air Ministry drawings) including a receiver room as well as rooms occupied by air filtration equipment, a telephone exchange, storage and a WC (no longer in situ). The footpath that approaches the west Rx block from the north has a concrete footbridge leading to brick steps dropping down to the bunker. The east block (at SY7461281682) appears to be a similar survival to the west Rx block, but with some remaining air-conditioning equipment and no lighting or other equipment. There is a HUT BASE to its south west that is ruinous and not of special interest.

To the north east is a STANDBY SET HOUSE (at NGR SY7477581836), a reinforced concrete structure with two doors (in offset positions to the east and west), roughly rectangular on plan with a roughly circular earth mound measuring approximately 31m east-west. Air Ministry drawings show buildings of this type and function with a principal generating set room, with the entrance flanked by a transformer room and a fuse room. The standby set house provided emergency power to the radar station. To the west, in woodland, is a small concrete and brick structure that may have been a GUARD POST (at NGR SY 7470081837).

The two Type C TRANSMITTER (Tx) BLOCKS (at NGR SY7514082066 to the east of Pitt Cottage, and NGR SY7580481687 200m west of Rose Cottage) housed the transmitter equipment which delivered pulses of high frequency energy from antenna erected on the four steel transmitter masts located at SY 75340 81595 and SY 74980 81673 (removed). They are rectangular structures, and are built of reinforced concrete and encased by a roughly circular earth mound measuring approximately 22m east-west. Each Tx block has two entrances (east and west) which are protected by concrete blast wing-walls, although the west entrance to the Pitt Cottage block has had its wing-walls removed and the entrance sealed. There are two concrete ventilators on the top of each Tx Block mound. The east entrance to the north Pitt Cottage Tx block has a later C20 timber door and adjacent to this is the transformer room with late C20 double timber doors. These doors are not of special interest. The interior was built as per standard Air Ministry plans, including an alcove with opening for the transformer cabling, but has seen some later alterations in brick, the removal of a concrete door lintel, and the insertion of later doors and doorframes. There are metal fittings to the ceilings and walls of the interior and some of the ventilation trunking also survives, along with plain timber architraves and concrete beds or pads set in the floors with transmission equipment fixings. In the room to the north are compartments with timber surrounds and there is a former WC to the rear passage. There are two ventilator openings to the roof. The south transmitter block (west of Rose Cottage) has a whitewashed interior and appears to have had most fittings removed. Two concrete ventilators protrude from the roof.

To the east of the north transmitter block is the Type C SUBSTATION (at NGR SY7557582045, to the south west of South Down Farm), earthbound and built of reinforced concrete to an Air Ministry standard design, and measuring approximately 18m east-west. It housed the mains transformer equipment for the site and is constructed of reinforced concrete and encased by an earth mound or traverse for blast protection. It has three entrances to its north-east, south-west and south-east elevations; each leading to a separate room.

History

RAF Ringstead was constructed in 1941 as a Chain Home radar station, and was fully operational by March 1942. Chain Home was a ring of early warning radar stations built around the coastline from the late 1930s and formed an important part of Britain’s Second World War defences. It was the first operational military radar system in the world, using technology developed on the simple principle of ‘floodlighting’ the surveillance area with transmitted pulses of radio-frequency energy. The pulses would ‘echo’ back from any aircraft to the ground station receivers. The range of the aircraft was measured by the elapsed time between the transmitted pulse and the return ‘echo’.

RAF Ringstead (officially known as AMES12B or CH12B) was one of the ‘West Coast’ Type of stations, a CH (West) site, which was designed with well-dispersed structures: ‘doubled up’ transmitter and receiver blocks, a substation and a standby set house (all in earth-bound bunkers), four 325ft steel transmitter aerial ‘pencil’ masts that stood on concrete pads with cables fixed out across the fields and curtain arrays, two 240ft self-supporting timber receiver aerial towers on foundation blocks, and other buildings such as dispersed accommodation and guard huts. Other, smaller associated structures such as latrines and Interrogation Friend or Foe (IFF) receiver cubicles were also erected. The dispersed arrangement and duplicate functions were intended to maintain operations in the event of loss as the result of attack, a design that improved on the earlier, less-dispersed ‘East Coast’ Type, which had proved vulnerable. However, an enemy bombing raid at Ringstead in September 1941 damaged the recently erected curtain arrays, which may have delayed the station being declared operational until March 1942. The radar station, with transmitter and receiver aerials in position, is shown on an RAF aerial photograph of 1947.

By May 1944 as the German bomber threat receded, and because of the high cost and manpower required to keep the Chain Home network operating, radar stations underwent a rapid contraction. From a peak of 194 stations in 1944, by 1947 only 36 remained, with only 29 of those manned at full readiness. Ringstead was stood down in 1945 and in 1952 was refurbished into a Rotor station site ‘SRD’, which operated until 1956. The Rotor programme was developed to update the existing wartime radar technology and to install more capable radar systems to detect and locate fast-flying jets. It was approved by the Air Council in June 1950. The first phase of the programme, Rotor 1, was to technically restore existing radar stations and put them under the control of RAF Fighter Command. There were three main components to the Rotor stations: the technical site, including the radars, operation blocks and other installations; the domestic site, where personnel were accommodated; and the stand-by set house, a reserve power supply. The technical site at Ringstead radar station was located at the former AMES12B and the domestic site was situated at Upton Farm around 2km to the north.

From 1963-1974 a USAF Troposcatter Scatter station was established at Ringstead to provide a cross-channel relay link from High Wycombe Atomic Joint Co-Ordination Centre to various US nuclear forces abroad. Two parabolic aerials were erected, and were dismantled in the 1970s. The various parts of the station have been redundant since that time and some alterations have been made to the transmission block by Pitt Cottage, including the removal of the west entrance blast walls and some internal works including the fitting of timber doors. This and the other structures have had many of their fittings removed. The CH masts have been removed, but the buildings and the concrete foundation blocks for the wooden masts survive. Some of the fixing points and pads for the two transmitter arrays may survive in fields, the westerly of which is protected under its inclusion in the Medieval Settlement at West Ringstead Scheduled Monument (1019393). Other minor related extant structures may also survive, particularly in the wooded areas around the receiving and transmission blocks. The former transmitting block in the grounds of Pitt Cottage is proposed for conversion to holiday accommodation in 2020.

Reasons for Listing

The former RAF Ringstead Chain Home radar station, Dorset, is listed at Grade II for the following principal reasons:

Architectural interest:

* as a substantially intact Chain Home radar station which retains its principal buildings and tower bases, which allow a clear understanding of how the site functioned;

* the radar station is one of the best preserved Chain Home stations in the South West, and as such as a rare example of its type.

Historic interest:

* as a physical manifestation of the tensions and fears of aerial attack during the Second World War, which addressed the need for a national air defence system;

* the Chain Home stations provided early warning of German aerial attacks, playing a crucial role in the air defence of the country during the Battle of Britain and changing the course of the Second World War.

Group value:

* the station has group value not only as a group of inter-related military structures within a cohesive station complex, but also with nearby Upton Fort (Grade II and Scheduled Monument) and other unlisted Second World War defence structures along this stretch of coast;

* further minor unlisted structures across the former base, some ruinous, together advance the appreciation and understanding of the operation of the radar station, and which continue the story of the development of radar and satellite communications from the Second World War through to the Cold War;

* the station structures are arranged outside the Medieval Settlement at West Ringstead Scheduled Monument.

External Links

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