Monument record BAW 051 - RAF Bawdsey, WWII Chain Home Extra Low Station K162, Chain Home Station CH26

Aerial photograph of early radio mast at RAF Bawdsey (S1).
The radio mast mentioned above was part of the experimental Chain Home radar system set up at Bawdsey in 1936. (S2). Erected in 1937 as part of the world's first radar station. Demolished in 2000 as too costly to repair (S8).
Photographs taken in the 1940s show a row of four towers and an associated building which is protected by earth and a blast wall. These towers would have been the transmitter towers for the radar station and the building would have been the transmitter block that housed the radar equipment. Immediately to the north of the masts there are a few lengths of barbed wire obstruction which would have acted as anti-invasion defences for the site (S3) (S4). The barbed wire had been removed by 1949 but all four towers remain in position until at least 1955. Two have been removed by 1965 (S5).
An Air Ministry Research Station to develop Radio Direction Finding equipment (radar) was established at Bawdsey Manor in 1936. In 1937 a training school was established and the station became the first operational Chain Home radar station in 1937. Chain Home stations commonly comprised transmission and receiver blocks, four 240ft timber receiver aerial towers, four 350ft steel transmitter aerial towers that stood on concrete pads, and other buildings such as dispersed accommodation huts, guard huts and standby set houses. During the Battle of Britain, the facilities at Bawdsy were important in providing early warning within the key 11 Group RAF Fighter Command sector, specifically for the southern North Sea and the Channel approaches. It also gave radar cover to help protect coastal convoys. The site was upgraded in 1942 and fitted with centimetric radar to become a Chain Home Extra Low station, called site K162. The site remained operational until 1952 when it was closed and refitted as part of the Rotor programme. The new station opened in 1953 to 1954 to the north of the Second World War site (BAW 185) and was continually refurbished and remained operational until 1975. The site was then used as a Bloodhound MKII missile site until July 1990. The site was included in the English Heritage Cold War Project. A survey in 1995 found structures and features surviving from all of the Radar Station's phases (S10).
The transmitter block still remained in 1996, as well as the mast (S1)(S6).
R3 double-level bunker - one of ten of this type built in England constructed to provide protected accommodation for the radar operators - a good example of a relatively unaltered R3 structure.
Also R17 Radar Modulator Building (1962) - housed modulators, switch gear and generators for Type 84 radar, which stood over the southern half of the building - one of four buildings of this type in England. In 1970 the Type 84 was dismantled and re-erected in Northern Ireland; the radar station remained operational until 1975 - subsequently used by the Bloodhound missile squadron based at the site and is included within its recommended scheduled area (S7).
Well preserved site at the home of British Radar. Remains include Receiver and Transmitter buildings, each with 4 sets of aerial base, with one radar still retained on APs from 1998. Buried receiver and transmitter buildings and attached aerials are in good condition. A number of accommodation buildings survive, including IFF, Guardhouses and 9 pillboxes (S9).

Bawdsey Manor was built in 1886 and enlarged in 1895 as the principal residence for Sir. Cuthbert Quilter.
During WW1 the grounds and stables were requisitioned by the Devonshire Regiment and having been returned to the Quilter family after the war the Bawdsey Manor Estate was selected as the site for a new research station for the development of radio direction finding in 1935.
The Treasury allocating one million pounds for the continuation of the research started at Orfordness. The Manor, estate buildings and 168 acres of land were sold to the Air Ministry in 1936 and Robert Watson Watt (a direct descendant of James Watt inventor of the steam engine) was appointed as Superintendent.
In January 1937 the RAF’s Radio Direction Finding (RDF) training school was established there and the first Chain Home radar station was developed on the site, coming on line in May 1937.
In August a filter room was established to process data from two other recently opened Chain Home stations, the tracking information obtained being used for the deployment of fighter aircraft.
The station was fully operational by 24th September 1937 providing long range early warning for the southern North Sea and the Channel approaches, as well as radar coverage for coastal convoys.
As well as research for the Air Ministry, a War Department (army) Team was working on the development of gun-laying radar that would enable anti-aircraft guns to fire accurately with poor visibility. By 1939 acceptable gun-ranging equipment was in service with an accuracy of 25 yards at a range of 10 miles.
Another important area of research was the development of an Identification, Friend or Foe (IFF) system allowing friendly aircraft to be differentiated from hostile planes. As a result of this research, aircraft were fitted with aerials incorporating motor-driven tuners that caused the reflected signal received by ground radar stations to vary in amplitude. Later models employed an electronic unit that detected the presence of friendly radar and then transmitted a coded signal causing the ground radar display to indicate a friendly aircraft.
By Easter 1939 15 Chain Home stations were available for use around the coast and Chain Home went into a 24 hour watch system.
On the outbreak of war the Research Station staff were relocated to dispersed locations around the country. Bawdsey continued in the forefront of the expansion of the radar network with an AMES Type 2 Chain Home Low on a 200 foot platform on the southern (No 4 of 4) transmitter mast. (Each mast was 350' high) This was able to detect low flying aircraft and coastal shipping but not small vessels or low flying aircraft just above sea level.
Towards the end of 1941 Coastal Defence Radar (Army CD Mk IV) was established at Bawdsey. This installation was taken over by the RAF on 7th December 1942 making Bawdsey the only site in the UK with three types of radar (CH, CHL and CD) in operation. By August 1943 Coastal Defence was changed to an AMES Type 55 Chain Home Extra Low (CHEL); again this was mounted on a 200 foot platform on the northern (No 1) transmitter mast.
In September 1944 Bawdsey began monitoring the launch of V2 rockets using specially developed Chain Home receivers codenamed ‘Oswald’. Although there was no defence against the V2 once it had been launched Oswald was able to provide Bomber Command with the location of the launch sites which could then be attacked. Other CH stations equipped with Oswald were RAF Stoke Holy Cross, High Street, Great Bromley, Dunkirk & Swingate.
The run-down of radar stations started before the end of the war from a peak of 194 stations in 1944 with only 36 remaining by 1947 and only 29 of those were manned at full readiness. Bawdsey is listed as being operational with both CH and CHEL in 1948.
In 1950 the station was chosen to participate in the ROTOR programme which involved the construction of a new underground operations room on a new 21 acre site on the north side of the Bawdsey Manor estate; this was planned to be operational by January 1952 as part of the ROTOR Plan Stage 1.
Towards the end of 1953, the Chain Home equipment was taken out of service and placed in a state of ‘care and maintenance’ and the Chain Home Low array was removed from the southern transmitter tower.
For the later history of Bawdsey Manor as fighter control school see RAF Bawdsey GCI Rotor Radar Station.
Today Bawdsey Manor is occupied by Alexanders International School, a residential language school. Many of the RAF buildings have now been demolished but the transmitter and receiver block, two buried reserves and a number of other buildings from all the major phases of the site still survive.
During WW2, RAF Bawdsey was identified as a potential target and in September 1939 was protected by three 40mm Bofors guns and two .303 Lewis anti-aircraft guns. With an increased fear of a German invasion, these defences were supplement in 1940 by slit trenches, sandbag gun emplacements, a concrete gun post and at least ten type 24 pillboxes; nine of these still survive. There were several attacks on the station during 1940 which did little damage with no casualties and on 18th October 1940 anti-aircraft gunners shot down a German bomber. Sporadic attacks continued over the following three years with some loss of life; the last bombing raid near Bawdsey was on 30th June 1944. A V1 rocket crashed on the beach on 21st September 1944 and a V2 detonated over the sea on 9th October.
RAF BAWDSEY TODAY
The main transmitter building is a single storey ‘A’ type (east coast) protected block which still stands in good condition. The transmitter building itself is 77' X 27' and of brick and concrete construction with traverses around the building. There is a 5' 6" layer of shingle on the roof to disperse blast. It is located in fields on the north side of the estate.
There are two access points through the traverses, one on the south face and one on the east face; these give access to an open pathway around the building between the traverse and the transmitter building itself.
The main entrance was originally on the south side with an entrance porch way and airlock. Internally the building is divided into a number of rooms comprising a lobby, air conditioning plant room, private branch exchange (PBX), latrine, transformer cubicle, sub-station, workshop and the main transmitter room. The building was equipped with a duplicate pair of Chain Home T3026 transmitters with a pulse power of 300 - 450 kW and a frequency range of 20 - 60 MHz.
The building still retains its wooden casement window frames and is Grade II listed; it is currently being restored to its original condition. A public open day was held there in July 2003. The concrete bases of the four 358 ‘high steel transmitter towers can still be seen in the fields on either side of the transmitter block. The truncated (280’) remains of No. 3 tower remained in place and used by the Harwich Port Authority until 2001 when it was demolished despite efforts to save it by English Heritage and the Royal Airforce Museum. The mast was in need of repair and was considered too dangerous to climb.
In the event of both transmitters being unusable a third transmitter was located underground in a wooded area 200 yards to the north east, this was known as the ‘buried reserve’.
This underground transmitter room still exists and is still accessible. The main access was by moving a three flat reinforced concrete covers on steel rollers and running rails. The two larger covers was for plant access and the smaller cover gives access to a steel staircase down 17' 5" into the bunker. One of the concrete covers is partly open but the stairway is badly rusted and is in a very dangerous condition and should not be climbed; the only safe access to the bunker being down the emergency escape shaft on the edge of the wood to the west.
At the bottom of the main stairway there is a lobby area with a gas tight steel door into the air conditioning plant room. The gas filter cabinet is still in place mounted on a concrete bed in the centre of the small room. There is a second small concrete bed against one wall; this would have been occupied by a suction fan. There are openings in the wall for the air ducting which has been removed.
Back in the entrance lobby there is also an air lock into the transmitter room. This consists of a pair of large gas tight steel doors into the airlock and a similar sized set of wooden doors out of the airlock into the transmitter room. The steel doors are still in place but the wooden doors have been removed. Beyond the air lock a doorway to the right gives access to a toilet with an alcove to the left of the air lock back to the wall of the air conditioning plant room. In an Air Ministry works drawing this alcove is shown as being partitioned off from the transmitter room and is identified as a rest room. There is no evidence of a partition ever existing.
On the north side of the transmitter room there is a large rectangular galvanised extraction hood suspended from the ceiling. This would have been immediately above the T3026 transmitter. There is a 5' X 3' gas tight steel door at ceiling level in the centre of the north wall with an offset steel ladder fixed to the wall for access to the escape tunnel which consists of a 13' low passage and at the end a vertical ladder. The ladder is not fixed to the brick wall at the top and the brick lined shaft is in poor condition with tree roots forcing some of the bricks out of position. The concrete surround at the top of the shaft has gone and the ‘hole’ is covered with a wooden pallet.
Close by there are five cement rendered brick ventilators with wooden slats for intake and exhaust ventilation. On the south side of the wood there are four concrete bases for the 120' high reserve transmitter mast and alongside the foundations of Research Hut 90 and the base of the fifth steel 358 ‘mast from the original Air Ministry Research Station.
The protected Type ‘A’ receiver block is of similar construction to the transmitter block although a little shorter at 60 feet in length. It is located on open ground to the rear of Bawdsey Manor.
The main entrance was through a central air lock in the north face with separate access to the transformer cubicle on the north side.
Internally the building is sub-divided into a number of rooms comprising office, plant room, switchgear room/sub-station, storeroom, latrine, receiver room and calculator room.
As the building is located very close the manor all entry points have been blocked to prevent casual access. Externally the building is in good condition with timber framed window casements still in place but bricked up.
Equipment would have included a receiver aerial switching and phasing unit, two Cossor RF8 (R32103) receivers and MkII or Mk III consoles with associated test gear including an electrical calculator which converted range, bearing and angle of elevation into grid reference points and heights in thousands of feet. (1940 version of a central processor unit on a modern computer)
The concrete bases of two of the four 240’ wooden receiver towers can be seen in surrounding fields.
In the event of both the receivers being unusable a third receiver was located in an underground chamber in a wooded area 250 yards to the east close to the eastern perimeter fence and cliff top. Externally the receiver buried reserve is identical to the transmitter reserve with a three flat reinforced concrete covers on steel rollers and running rails. The smaller cover is open and gives access to a steel stairway down into the bunker. Again the stairway is badly rusted and in very poor condition and should not be used.
The emergency exit shaft is in better external condition with its concrete surround and entrance hatch still in place. The brick lined shaft is in fair conditioning with some cracking.
The bunker is flooded to a depth of 15" with clear rainwater. At the bottom of the main stairway the layout is identical to the transmitter reserve with a lobby area and a steel gas tight steel into the air conditioning plant room. The gas filter cabinet is still in place mounted on a concrete bed in the centre of the small room.
The air lock into the receiver room still retains both sets of doors, the outer doors being of steel and the inner doors being of timber. Beyond the air lock a doorway to the right gives access to a toilet with an alcove to the left of the air lock back to the wall of the air conditioning plant room. Unlike the transmitter reserve this alcove is partitioned off with a wooden door for access and was, presumably, a rest room as indicated in the Air Ministry works drawing.
There is no extractor hood as receivers don’t generate the same heat as transmitters. At the back of the room there is a 5' 3" gas tight steel door at ceiling level in the centre of the north wall with an offset steel ladder fixed to the wall for access to the escape tunnel. Apart from the water the receiver buried reserve is generally in better internal condition than the transmitter reserve. The paintwork is in good condition and several metal lamp shades are still in place.
Externally there are five rendered brick ventilators all with their wooden slats missing and the base for the 120' receiver tower can be seen in the undergrowth nearby.
Close to the perimeter fence on the east side of the wood there is the distinctive concrete base (in the shape of a cross) of the IFF aerial mast while the brick IFF cubicle itself is located in undergrowth outside the perimeter fence close to the cliff top.
A number of other RAF buildings still survive, the most substantial being the Senior NCO’s mess (formerly the filter school) and the Airmen’s Barrack Block (Formerly the research Block). Both are large two storey brick buildings located alongside the road running through the estate. They are now used as class rooms by Alexanders School. A small pink RAF hut alongside the NCO’s mess was the Bawdsey Ferry post office, unusually located within the Manor grounds.
The standby set house was at the northern end of the site, this was retained and rebuilt as part of the 1950’s ROTOR complex and is now in separate ownership.
On the west side of the manor, behind the car park a two storey white building with a tall brick tower was a gas decontamination centre, an air raid siren still remains in place on top of the tower. A number of MT garages still survive on the east side of the manor and the guardhouse and armoury still stands at the main entrance to the estate at Bawdsey Quay with a smaller picket post at the rear entrance. All buildings from the rotor period have been removed. Outside the estate on the approach road to the Quay, the married quarters are now in private ownership (S12).