Chain Home radar at Scarlett

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By September 1941 Chain Home coverage was complete except for north-west Scotland. The Manx radar stations covered Liverpool, Belfast and a large part of the Irish Sea.

The Isle of Man was home to a wide variety of military installations during World War II. They included the Chain Home radar stations at Dalby, Bride and Scarlett (always spelled ‘Scarlet’ by the RAF). This highly secret system was developed in the late 1930s to provide advance warning of enemy bombers and was the first major operational radar system. By the start of the war nineteen stations covered the east coast of Britain from Scotland to the Isle of Wight.

By 1941 the chain comprised about 200 stations and had been extended to the west coast with only north-west Scotland unprotected. Chain Home proved its worth during the Battle of Britain when Germany sought to gain air supremacy in readiness for the planned invasion of Britain. Chain Home allowed the small force of British fighters to be directed to the appropriate points for interception of attacking aircraft.

Chain Home aerial systems.

No photographs are known of the aerials at Scarlett, but they were of the same type as these at Dalby. The pair of wooden towers on the right had receiving aerials near the top. The transmitting aerials were slung between pairs of metal masts. One pair can be seen at the left of the photograph, which was taken from one of the other duplicate transmitter masts. Photograph by John C. Hall, 1949.

Chain Home radar stations were positioned so as to provide a clear view over the sea. Unlike modern systems, such as Ronaldsway Airport radar, which sends out a narrow radio beam scanning the surrounding area, Chain Home had large static aerials. The transmitter aerials at Scarlett were suspended between 325 ft high steel masts stabilised by steel guy ropes and the receiving aerials were mounted in 240 ft high wooden towers. WAAF operators in the operations room used electronic and electro-mechanical aids to calculate the height and bearing of friendly approaching aircraft.  Friendly aircraft were fitted with special radio equipment (IFF) which responded to the Chain Home radar signals and allowed them to be identified on the radar display.

Receiver block and operations room at Scarlett.

The earth covering is eroded and the camouflage netting is long gone. Photograph by Alan Cleary, 1994.

Each Chain Home station was staffed by 63 RAF and 60 WAAF personnel, mainly officers and NCOs. The stations worked around the clock – four shifts per day. Any reports of sightings were passed on by landline to Fighter Command.

Chain Home radar was unable to detect low-flying aircraft and surface vessels. It was therefore supplemented in 1940 by a system, known as Chain Home Low, which was more similar to modern radar. The bases of the buildings for the Island’s Chain Home Low station may still be seen at the top of Mull Hill.

In 1941, the substantial blast-proof reinforced concrete buildings for a Chain Home radar station were constructed on the land of Scarlett Farm and its surroundings to the south of Castletown. These technical buildings, most of which are duplicated, included a transmitter block, a receiver block, an operations room, and a generator house. The station also included barracks blocks and guard posts for army personnel.

In 1944, the radar station at Scarlett was closed and its domestic site (where the RAF and WAAF personnel were billeted) was taken over by 1948, the Royal Naval training station, HMS Urley, at Ronaldsway. In 1948 the buildings at the domestic site were linked together by corridors to form the basis of Castle Rushen High School. The official opening of the School took place on 6th May 1949, and was accompanied by the publication of a booklet by the Education Authority.

The booklet included plans of the site both before and after the conversion (also reproduced on page 3 of the recently published Castle Rushen High School 1948-1998). Although a modern school building was erected on the site in 1962, part of the original wartime building is still incorporated in of one of the changing rooms.

Map showing Scarlett Farm (map reference SC254671) and the main Chain Home structures:

TxA: transmitter aerial, RxA: receiver aerial, Tx: transmitter block, Rx+Op: receiver block and operations room, Rx: receiver block, Gen: generator house

The technical buildings at Scarlett Farm have long since lost their camouflage netting and much of their earth covering. They are now in semi-retirement serving as over-engineered farm sheds and animal shelters. The barracks blocks that were occupied by army personnel can still be seen from the coastal foot path and a semicircle of pillboxes still guards the inland side of the site of the Chain Home radar station that was at Scarlett.

Contributed by Alan Cleary.