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Introduction
These are records of the work carried out by the research staff together with the drafted personnel from the Services particulaly related to the Interservices Ionosphere Bureau. As we find copies a link will be added to the entry with others listed awaiting identification.
We have recently discovered details of the full involvement of the Company which are detailed here and in list below:
HW41/401 - a set of lists of UK Y stations - Y Stations lists and locations Oct 1941 to Aug 1945
All references to Chelmsford, Bedells End and Ford End are Naval. None feature in RAF, WO or FO lists.
11/10/41 - Chelmsford Postal address Bedells End, N. Chelmsford Map ref M124272 Sole mention of Bedells End in file.(Chelmsford)
17/12/41 - Chelmsford Now designated "Experimental D/F", linked to Marconi and Baddow?
RAF site at Kingsdown is also Experimantal D/F. No others are designated like that.
12/1/42 - Chelmsford Q - The Q indicates a research site. No others are designated Q at that time
25/6/42 - Chelmsford Q - Now listed as inter-service rather than just Naval. Only station to have that tag. Link to Baddow and the IIB at
Baddow? The change to inter-service ties in with the setting up of the IIB which links Chelmsford to Baddow.
10/5/44 - Chelmsford Q - Abbotscliffe and Ventnor both designated as Q. However Chelmsford is always only Q, the other two are N, O, P as well as Q
M=Main Intercepting. N=D/F. O=VHF Intercepting. P=Non-Morse Intercepting. Q=Research
12/6/44 - List of all stations - Chelmsford Q - M124272 Note - the Chelmsford site is listed separately to Ford End
Ford End - M102352 - HF/DF Group Appears without prior mention - no other similar group listed
(Chelmsford) - M10535 - covers six map refs
M111349
M118350
M122347
M121344 Control Room
No further changes regarding Chelmsford or Ford End.
Additional suppositions
Chelmsford was not a normal operational Y or D/F station. It might well have functioned as that but as part of its experimental research work. Given its location that research must have been at Marconi and involve Baddow.
However there is no solid proof for that but it is hard not to draw that conclusion. The timing of the change to inter-service does fit with the IIB being set up.
This map shows the probable location of the Bedells End Y site on the Roxwell Road out of Chelmsford (roughly where the blue line is). In 1956 there was still a hut located in the centre of a rhombic array where HFDF research was being carried out by Dennis Byatt. The main Writtle site was located further down Lordship Road near the village.

The Ford End HF/DF group suddenly appears in June 1944 using six sites.
Additional sources
CARS meeting here
List of activities
Centimetre waves effects of refraction; Eckersley T L; Air Ministry Great Baddow Research Laboratories; March 1942; TR/434; RAF 5
The investigation of horizontally and vertically polarised direction finding of frequencies of the order of 20 to 70 megacycles per second; Eckersley T L; Air Ministry Great Baddow Research Station; September 1942; TR/451; RAF 5
Short wave direction finding; Eckersley T L; Air Ministry Great Baddow Research Station; 1942; TR/454; RAF 10
The calculation of oblique-incidence transmission; Cox J W; Baddow Research Laboratories; November 1942; TR/434; RAF 11
1 to 10cm propagation curves; Millington G; Baddow Research Laboratories; January 1943; RD 460; RAF 19
Abnormal region-E ionisation; Eckersley T L; Air Ministry Great Baddow Research Station; March 1943; TR/464; RAF 13
Non-linear theory of wave propagation; Millington G; Baddow Research Laboratories; March 1943; RD 580; RAF 45
Transmission over ground of varying earth constants; ; Air Ministry Great Baddow Research Station; July 1943; TR/473; RAF 23
The LORAN system; Eckersley T L; Air Ministry Great Baddow Research Station; 8 September 1943; TR/475; RAF 28
Scattering; Eckersley T L; Air Ministry Great Baddow Research Station; November 1943; TR/481; RAF 49
The effect of the geomagnetic field on electromagnetic waves vertically incident on the ionosphere; Cox J W; Air Ministry Great Baddow Research
Station; December 1943; TR/477; RAF 34
The attenuation of short radio waves by vertical reflection from the ionosphere; Cox J W; Air Ministry Great Baddow Research Station; January 1944; TR/478;
RAF 33
The propagation of ultra-short waves round hills and other obstacles; ; Air Ministry Great Baddow Research Station; 18 November 1943; TR/479;
RAF 41
Height-gain tests in the troposphere; Isted G A; Air Ministry Great Baddow Research Station; July 1944; TR/488; RAF 39
The reflection coefficient of a linearly graded layer; Section āEā; Air Ministry Great Baddow Research Station; September 1944; TR/492; RAF 50
Preliminary analysis of Height-gain tests in the troposphere; L/AC McDowell R F C; Air Ministry Great Baddow Research Station; September 1944;
TR/494; RAF 43
A note on the reflection coefficient of an isotropic layer of varying refractive index; Millington G; Air Ministry Great Baddow Research Station;
5 October 1944; TR/497; RAF 48
Alexandra Palace tests; Eckersley T L; Air Ministry Great Baddow Research Station; October 1944; TR/498; RAF 52
Polarisation measurements on reflected waves on 1.9 mc/s; Section āEā; Air Ministry Great Baddow Research Station; December 1944; TR/500;
RAF 53
Awaiting - TR456
There are also some referencing other work for the Admiralty:
A mercury-pool switch with electrostatic ignition; Baldwin Banks G; Great Baddow Valve Group; (ADM290A); December 1943; Box 2064
A wide range reflection oscillator valve (OT.48); Baldwin Banks G; Great Baddow Valve Group; (ADM294); January 1944; Box 2064
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