Britain's HF Radio Heritage: Diplomatic Wireless Service

The Diplomatic Wireless Service

The main gate at HMGCC Hanslope Park. This is the most that 99.999% of us will ever get to see...

Work in progress...

The roots of the Diplomatic Wireless Service lay in MI6 and their wartime operations at Bletchley Park. There was also the Radio Security Service, or RSS, which included the Y service which had been responsible for intercepting radio traffic in occupied Europe. Shortky after the war ended, these were combined into the DWS which was officlially inaugurated and moved to its headquarters at Hanslope Park, where its succesor organisation the Her Majesties Government Communiocations Centre still operates.

The core business of the DWS was to provide communications links with British Embassies worldwide. In order to handle this, transmitter facilities were established at Crowborough (the famous former home of the 'Aspidistra' transmitter used for propaganda against the Germans in ww2), at Gawcott in Buckinghamshire and possibly other locations. There would also likely have been associated receiver stations. There were also considerable facilities located on foreign soil.

Some of the DWS transmitter facilities were used to transmit BBC World Service programmes, in the UK this included Crowborough and Orfordness.

There is much rumour and speculation about the DWS involvement in clandestine and covert operations involving MI6 (and/or/other) organistaions; and the tendency of writers is to focus on the 'glamourous' side of the story to the neglect of the (still interesting) mundane.

Can I just say that the problem with researching subject matter such as this is that the internet is full of stories that get rehashed time and time again until they end up a bit like a fourth-generation copy of an old VHS tape- highly distorted. And then there is the plain rubbish, such as the cold war paranoia and the conspiracy theorists and this I will simply disregard. So we will stick where possible to the facts as they are able to be determined at first hand from trusted sources, and where there is an element of speculation, I will clearly state this.

Quick History As stated above, the genesis of the DWS was the coming together of a number of smaller services after WW2. This is included the acquisition of a number of existing facilities. These are listed below with any references that can be found. The DWS became the Communications Department of the Foreign and Commonwealth Office in the late the 1980's but with technical facilities being provided by HMGCC, which does appear to be mainly an engineering organisation.

Hanslope Park
The headquarters building, according to official histories, was a receiver station but when computers became available, it became the computing centre as well- I have to say I'm not sure how 1960s mainframe computers with all those thirsty TTL devices would have co-existed peacefully with HF receivers but perhaps they did. The successor organisation, Her Majesties Goverment Communications Centre is still at Hanslope but there is nothing to see from any of the surrounding roads, and you get the impression even stopping the car to look would soon result in you being moved on.

There is no trace of any antennas visible on Google maps.

Gawcott is located at 51.981457 N, 0.993919 W or about 2.5km SW of the centre of Buckingham. The station was probably built in around 1940. The first transmitter to be installed was an RCA 10kW type, which was erected in a wooden buidling. Power was provided by a Ruston generator set. This transmitter was soon joined by a second, this being built in a brick enclosure and powered by its own Crossley generator. Both has blast walls erected around them, and the whole site was protected by, allegedly, an electrified fence. Within each of the transmitter buildings were two turntables by means of which which pre-recorded programme material could be played. The turntables ran at 33.3 RPM and played from the centre of the record outwards. When the record was delivered to the site, it was labelled with the frequency to use and the antenna i.e. the transmission direction.

And thus begins one of the more bizarre episodes in the history of broadcasting in the UK. The programmes, transmitted in the evening, had the callsign Gustav-Seigfreid-Eins (GS1) and were presented by 'der Chef' (the chief) who claimed to be a disaffected Nazi located within Germany. Aimed at the gneral public, the presenter was scathing about the English but named high-ranking officers within the German military and government, and gave away highly explicit detail of their perversions and sex lives (see ref. 3 for detail and examples). To perpetuate the story that GS1 was located in Germany, this bizarre station eventually closed down following an elaborately staged 'Gestapo attack' complete with the sound of gunfire. Some time later it re-appeared in different form as the 'Soldatensender Calais' with a different programme format aimed at German service personnel. This became Soldatensender West and moved to Crowborough, to be carried by the famous 500kW Aspidistra transmitter; although one likes to think that the SS will have spent a lot of time fruitlessly searching the Calais area first!

After the war, and following the formation of the DWS, Gawcott became the transmitter site for Poundon, it also transmitted for Hanslope however the primary tx site for the latter was at Creslow.

It is often speculated that the numbers station The Linclnshire Poacher was transmitted from Gawcott, however I can state with authority that this is in fact not the case. No telephony transmissions ever took place in the post war era; they were all either CW or RTTY, with FSK and multitone data systems coming later.

The site has now been sold off for redevelopment, and it looks as if the old buildings are being demolished. There is no trace visible of any antennas on the site, except for a strange cross visible on the ground on aerial photographs. This is the same size and orientation exactly as the ground mark below an existing antenna at RAF Croughton.

(Left) odd ground mark at Gawcott (right) Antenna at Croughton: same scale.

It is now known that this antenna was for an ionospheric sounder; it consisted of 4 log periodic antennas (for north, east, south and west) laid out in the form of a cross and supported by a central mast.

Poundon radio station is located east of the village of Poundon near Bicester in Oxfordshire. It was undoubtedly a communications station, with an antenna farm but it was also the DWS training college. During the war, Poundon belonged to the SOE but there is evidence it was also was used as an intercept (receiving) station providing the raw material for Bletchley Park's famous codebreakers. Part was decommissioned in 1969/70; but other parts were still operating up until very recently (2012?) when it was sold off and has now become Tower Hill industrial park.


Far more fruitful from a point of view of aerial exploration is this former transmitting site located at 51.04275 N, 0.104059 E or 5km WSW of Crowborough, East Sussex. An underground bunker housed the famous 500kW Aspidistra transmitter, although when this was installed there was already other transmitters on the site, including HF transmitters loaned by the BBC that had been dismantled at Woofferton and re-erected at Crowborough. Although a DWS station, Crowborough was used by the BBC for broadcasting the World Service on Medium Wave and Short Wave. Frequencies in use for this were 1295, 1088, 809 and 648KHz and also a frequency in the 31m band. This accounts for five of the ten trnsmitters known to be at the site, so what the other five did is not known but I would speculate that they were used for diplomatic links.

The wartime use of 'Aspi' for propaganda transmissions is well known. Slightly less well known is the fact that an attempt was made to jam the V2 rocket bombs from here- on VHF. Parts recovered by intelligence agents from V2 crash sites in mainland Europe included what were obviously radio receivers and this had led Dr. R.V. Jones, scientist to the War Department, to speculate that the V2 was radio controlled. This theory was supported by the reports of reception of strong radio signals, again by intelligence agents, when a V2 test flight took place. If it could be jammed, Jones reasoned, then perhaps the weapon could be disrupted and would either fly safely off course or not detonate its warhead of high explosive. Measurement of the tuned circuits from the wrecked receivers indicated two frequencies were in use, one around 50MHz and another around 165MHz. A huge transmitter was built, using large water cooled valves taken from short wave transmitters arranged in a self-excited oscillator circuit.. When V2 launches were detected, the transmitter was fired up and all fingers crossed.

In the event, the radio receivers found in the wreck were only used in test weapons launched from Peenemunde and 'production' rockets were steered by gyros. However, the efforts of those concerned in this attempt must not be underestimated- it was a gallant and inspired attempt to save British lives. It also illustrates a point aboout the limits of intelligence; even when processed by a brilliant mind.

There are many histories of Crowborough and the Aspidistra on the web; there is little point in reproducing it again here.

St Helena
The island of St Helena was a site of a DWS radio station from 1966 until the late 1970's. It was a relay station, relaying multitone (piccolo) transmissions from embassies.

There is an interesting article on the St Helena web site:

About Piccolo
Piccolo was a multiple tone radio modem system invented by H. K Robin, D Bayley, T. L. Murray and J. D. Ralphs. Details were published in Proc IEE vol 110 No 9 September 1963 pp 1554-1568 and were announced in a paper presented at the Convention on HF Communication 26 March 1963. The authors worked at the time for the "Diplomatic Wireless Service of the British Foreign Office".

The principle of piccolo was to encode the 32 possible teleprinter characters as discrete tones, starting at 330Hz and going up in 10Hz increments to 640Hz so (in letters shift) 330Hz was A, 340Hz was B, etc up to 650Hz for LETTERS_SHIFT and 640Hz for BLANK. The system was electromechanical and could read 5-unit Baudot code teleprinter punched tape, which was optically scanned and a matrix used to select the required tone. At the receiver station, the incoming tones were applied to a bank of 32 tuned circuits which were kept just below oscillation by positive feedback. Each tone would resonate one tuned circuit, and a following level detector would provide a signal that was fed to a 32 to 5 line diode matrix. A mechanical shift register clocked out the individual bits, adding the start and stop bits, and thus generated a standard serial stream for connection to a teleprinter. Synchronisation was achieved by a master oscillator that was used to drive an induction motor, that operated the electromechanical parts of the system. The outputs from the resonant circuits and their level detectors were OR'ed to give a signal with a 10Hz component due to the finite time it took for each circuit to resonate. A phase detector compared the phase of this signal to the scanning motor and drove a variable capacitor tuning the master oscillator one way or the other, to maintain synchronisation even if the signal faded right out.

The system was housed in a cabinet 22 x 21 x 26 inches; a single unit could be switched between transmit and receive; 2 units could provide a duplex link. In terms of perfomance, the system was claimed to be 15 dB better than wide band binary fsk, 2db better than any other bit by bit encoding system, and within 8db of the Hartley-Shannon law limit.

Piccolo had a very distinctive sound, in fact the name derives from the similarity to the sound of the musical instrument. Note that piccolo was not in itself an encryption system; the tapes to be sent would have been encrypted first using an offline tape-to-tape system like Rockex.

Under construction: please check back again soon!


If you have any information about transmitter and receiver sites please contact me at alancordwell[at]blueyonder[dot]co[dot]uk.

  1. Pat Hawker writing in 'Radio Bygones' Issue 31 Oct/Nov 20 PDF Document (off site link)
  2. Simon Mason, web site 5344'N 026'W about number stations Web Link
  3. PsyWar web site, article about GS1 based on FoI act request Web Link
  4. Piccolo radio teleprinter system; authoritative reference Web Link
  5. Piccolo radio teleprinter system, audio clip Audio Clip (wav format)
  6. Subterranea Britannica article on CrowboroughWeb Link

Last Modified 10/12/2015