Site Records


Site Name: RAF Chenies ('HAM') R8 GCI ROTOR Radar Station

Chenies Hill
Chenies, Hertfordshire
OS Grid Ref: TQ015997

Sub Brit site visit 10th November 2004

[Source: Nick Catford]

RAF Chenies was an R8 Ground Control Intercept (GCI) radar station (code HAM) built in the 1950's as part of the post war ROTOR Programme. While most post war GCI stations utilised an existing WW2 site, Chenies was a green field site. Originally sited at Heathrow, it was known by this name until it was changed to Down Barns and on 5.9.1950 the name was changed again to Chenies.

Chenies was built as part of the first stage of the ROTOR Programme which was itself divided into four phases. Phase 1 was the re-establishment of 28 WW2 Chain Home radar stations. 13 were brought up to a fully operational state while the remaining 15 were brought up to a 'readiness' state. These stations would have required some notice before they were fully operational.

Photo:RAF Chenies - The R8 operations block is to the rear with the high voltage switch house in front. The standby set house is in the middle of the picture with the modern Met Office radar on the right.
Photo by Nick Catford

Phase 2 was the construction and installation of 14 new underground Centimetric Early Warning (CEW) and Chain Home Extra Low (CHEL) stations. Phase 3 was the construction and installation of 11 new underground GCI stations Phase 4 was the construction of 14 new semi-submerged or above ground GCI stations. These were generally (but not always) located on the west side of the country where the perceived threat of attack was not so great and to save on cost protected underground accommodation was therefore not provided.

Phase 4 comprised of five R6 semi submerged protected stations and nine less substantial R8 stations. Normally, stations on the east side of the country would be protected but Chenies being in the centre of the country was provided with a prefabricated SECO R8 structure built of wood fibre and asbestos panels. Of the nine R8's, Chenies was the only station to be fully operational, all the others were 'readiness'. The other R8 technical blocks were at Calvo, Charmy Down, Comberton, Gailes, Hartland Point, Scaranish, St. Anne's and Trewan Sands. Two further R8's were later built at Killard Point (Ballywooden/Bishopscourt) in Northern Ireland and Wick in Scotland as part of the Rotor 3 programme.

Plan of RAF Chenies
Surveyed & Drawn by Bob Jenner

By 30.8.1953 the first two phases of the ROTOR programme were finished and Phase 3 buildings were complete with the installation well advanced.


Type 14 radar

By this date the fourteen Phase 4 technical blocks which comprised five semi-sunken R6 structures and nine prefabricated R8 structures were nearing completion with technical installation expected to be finished by early 1954.

RAF Chenies had no married quarters or domestic camp with personnel being billeted at three of the dispersed sites of RAF Bovingdon, two miles north of Chenies from where they were bussed in daily.

The following radars were originally planned for Chenies: one Type 14 Mk. VIII, one Type 14 Mk. IX, two Type 13 Mk. VI, one Type 13 Mk. VII, one AN/FPS3 and one AN/TPS10. (No Type 80 was planned or built at Chenies).

It is unclear when Chenies came became operational but in 1954 '163 Signals Unit, Chenies' replaced the Fighter Command Control Unit at Heathrow, It is clear the station was not completely ready at this time as a temporary Type B operations hut was required for the AN/FPS3 radar.

The ROTOR station at Chenies was however short lived closing as a radar station prior to 'The 1958 Plan', the successor to the Rotor Plan.

In 1959 Chenies was awaiting disposal but along with RAF Bovingdon it was selected as an ideal site for the construction of underground silos for the Blue Streak missile programme. Disposal proceedings were immediately stopped but the project was later cancelled due to its apparent lack of credibility as a deterrent


In 1956 a 90 Group Vickers Varsity calibration aircraft visited RAF Bovingdon to calibrate the radar equipment at Chenies. This meant flying outbound and inbound tracks to the Radar station on various headings. The photo shows the navigator of the Varsity at his plotting station. - Photo by Town Dawes

Photo:RAF Chenies in 2003
Photo copyright Defence Estates

The station remained in RAF hands however becoming a Strike Command communications facility. In the mid 1980's Chenies also took on a new role as part of the Gandalf Project when a new radar was installed for the Met Office. The new radar is one of a network of Met. Office C band radars, situated north-west of London. It provides high-resolution (2 km Cartesian grid, 5 minutes time interval) estimates of precipitation intensity and extent over the south-east of England and is partly funded by the Environment Agency.

Photo:RAF Chernies during its days as a Strike Command Radio Station
click photo to enlarge

For further information and pictures of RAF Chenies click here

[Source: Nick Catford]


Last updated 22nd January 2005

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