Ongar Radio Station – North Weald 1939-85 (Part 2)

The Second World War. The war- and the immediate period before brought many changes. The files are not complete but record the following events.

September 1938. Instructions were issued about air raid and blackout precautions. The radio station was to close down on receipt of an air raid warning. Lengthy instructions were given on the construction of ‘garden trenches’ as air raid shelters. These were simple trenches with a timber roof covered with earth, closed off with a wetted blanket to form a gas curtain.

September 1939. A single line from Electra House, Embankment was installed in case Electra House, Moorgate was put out of action. Further blackout instructions were issued, and the previous instruction to stop transmissions during air raid warnings was revoked (with the exception of long wave transmissions).

December 1939. Qualified volunteers were being sought to listen for illicit transmissions. Ongar Radio Station was listed as a "key point" of national importance, carrying an obligation to notify the County ARP Controller of full details of any damage or sabotage.

May 1940. A trial of the emergency arrangements from Electra House, Embankment took place, with the disconnection of all lines from Moorgate. The redoubt was being used as an air raid shelter for non- essential personnel during air raids. Instructions were given that the plant should be shut down, and all lights extinguished, if the skylights of the transmitter hall or power house were blown out. Armed police were on duty and staff were advised for their own safety to stop promptly for identification on being challenged.

June 1940. Further instructions were issued to cover the possibility of the destruction of the Central Telegraph, Electra House, Moorgate. Ongar's transmitters were to be controlled by London through the five Brentwood Radio Station tone sender channels. Mast warning lights were not being switched on at night, except on special request from North Weald airfield.

August 1940. There was a visit by General Sir Walter Kirke to advise on protective measures. He advised that the proximity of "a considerable garrison" at the neighbouring airfield reduced the risk of sabotage, but increased the risks of attack by air. He felt that the aerials were not particularly vulnerable, but that it would be advisable to maintain a store of materials for making temporary aerials, or repairing damaged ones. He noted the presence of six armed policeman, day and night. Round the main
building was a concertina wire fence with several gaps in it! He wanted this fence heightened and the gaps closed with "knife rests". He noted that personnel at the station numbered about 60, 23 of whom were in the Home Guard. The station had twelve rifles which could be used from three defensive posts "erected by the Military". He recognised that the main buildings were highly vulnerable to air attack and that nothing could be done to alleviate this. He recommended the building of 14 inch thick brick blast walls outside all ground floor windows, to protect both personnel and equipment from flying glass in the event of a near miss. Firefighting equipment was limited to stirrup pumps and chemical extinguishers. As the cooling ponds contained about 50,000 gallons, he advised the acquisition of a trailer pump and hoses to improve firefighting capacity. A small brick building provided for this on the access road just to the east of the Redoubt.

September 1940. Royal Artillery Officers visited to agree a site for one or two anti-aircraft guns. Field 17 was chosen, midway between the railway and the house of the Engineer-in-Charge, Mr L.D. Hill. The latter was concerned about the proximity of a high tension feeder cable, and felt that the guns would increase rather than reduce the vulnerability of the station to attack

November 1940. Sufficient barbed wire arrived to erect a breast high fence nine feet deep, running 50 to 60 feet from the main building, with removable ‘knife rests’ for the roadways. Camouflage officers from the Directorate of Camouflage at Leamington Spa visited the site.

September 1941. Instructions were received that in the event of invasion, civilian personnel were to remain at their posts until the last moment, when the radio station should be ‘immobilised in accordance with the scheme already agreed’. The Vulnerable Points Adviser was anxious that all but one entrance to the main building should be blocked to make the guard more effective.

October 1941. The question of camouflage rumbled on, nearly a year after the first visit of the camouflage officers. There was concern the difficulty in obtaining materials, and the risk of fire due either to sparking (‘which could he reduced by earthing the fence wires at regular intervals’) or from incendiary bombs. The scheme involved constructing artificial hedges and trees with posts, wires, brushwood and ‘tree tops’. The hedges were to vary from five to ten feet in height, with ‘tree tops’ mounted at twelve to fifteen feet on posts. A complicated netting scheme was devised to conceal the redoubt but eventually this proved too complicated, and the area was planted with trees.

November 1941. Cable and Wireless were still having doubts about the camouflage. One scheme alone required 20 miles of wire and a very large number of wooden stakes. The military authorities were insistent, and felt that camouflage was essential. The cost was to be split equally between the Government and the company.

September 1042. Cable and Wireless noted that the camouflage scheme was only partially completed, and that on the aerial photographs the barbed wire was conspicuous, and the artificial trees were ineffective!

A Civil Defence document, dated 1/9/1952, listed the defence measures which had been undertaken at Ongar Radio Station during the 1939 – 1945 War antiblast walls in 14 inch brickwork were built to protect ground floor windows at T" station, the office block and the power house. All Window glass was covered with cellophane tape or brown paper, and plywood black-out screens were made for the upstairs windows. Outdoor air mid shelters constructed of steel and covered with four feet of earth, with bench seating for twelve, were provided at "C" station and the power house. Concrete blockhouses were constructed inside "C" station and the power house, and two steel domed look-out shelters were installed by the
military authorities on the earthworks of the redoubt. The main buildings were enclosed by a coiled barbed wire screen, with double gates at the entry point. The sentry boxes here were manned first by Special Constables, then by the Home Guard and subsequently by the Military Police. Firefighting provision consisted of a static water pond close to WC station, and a trailer lire pump. Precast concrete air raid shelters were provided at the stall houses, and steel helmets for all employees. An auxiliary telephone switchboard was installed in the redoubt for use by staff if "C" station had to be abandoned. There was also a 150 mHz radio link with Electra House which provided a VHF link for carrying six tone channels if the landlines were disrupted, with the necessary aerial mounted on top of one of the beam aerial masts. Finally there was a petrol engine generator set of about 5 kw in the ex GLB feeder hut, together with a low power transmitter and receiver, operating on 5 mHz.

Apart from a direct hit on the power house (necessitating extensive repairs to the battery room), and damage to one of the beam aerial masts by a VI flying bomb, Ongar Radio Station escaped damage.

Further developments and expansion. In December 1943, “D” station was opened, three quarters of a mile east of "C” station and just north of Ongar Park Farm. This contained five unattended short wave transmitters, remotely controlled from "C” station. The frequency of one of these could be changed quickly by remote control to one of four pre-set frequencies. A later commentator wrote “In 1943, a star exhibit of the station was the 20 kw transmitter which could be started up, any one of four frequencies selected, and the transmitter tuned and connected to the right aerial – all in twenty seconds. This however necessitated the use of numerous electric motors, chains and cams, far removed from the sophisticated circuitry ...which we are pleased to accept and put into operation today".

The next development was "E" station, completed in December 1946 just to the south of the bridge over the railway cutting. This had a further six remotely controlled Marconi SWB 8/10 transmitters, though frequency changes required a visit by technical staff. However, aerial direction was remotely controlled from "C" station.

A staff list of November 1949 shows that a work force of 91 was required to keep the station running 24 hours a day. There were 42 technical staff working in the transmitter hall and power house, 15 staff (riggers, fitters, electricians and labourers) looking after the aerials and feeders, and a further 18 classified as "skilled and unskilled" working in "C" station and the power house. Six labourers worked on site and road maintenance, and two store keepers, four clerical staff and a total of six mechanics, carpenters and a lorry driver completed the staff.

Under the Commonwealth Telegraphy Act of 1949, all UK radio services run by Cable and Wireless and the General Post Office were integrated on 1/4/1950, and Ongar was controlled by the GPO Engineer-in Chiefs office from that date. Three years later, control passed to the External Telecommunications Executive.

The rapid growth in demand for radio telex and radio telegraph circuits necessitated the installation of seven remotely controlled 30 kw DS13D S.T.C. IBS transmitters at "D" station in 1959. These had remote wave change facilities, with a choice of six pre-set frequencies between 4 and 27.5 mHz.

Safety considerations were becoming more important, with oil filled
equipment enclosed in a fire proof space, and the transmitter cubicles interlocked with the main power supply so that access was impossible until the power was off. The older transmitters with water cooled valves were enclosed in cabinets by 1955. In 1957, the original Vickers-Petters diesel generators, with their potentially lethal hot bulb ignition, were replaced by diesel power units capable of generating 1.5 mw.

New transmitters required new aerials, and "D" station was provided with rhombic aerials slung in pairs between masts - the upper aerial for 4 to 12mHz and the lower one for frequencies above 12 mHz. Remotely controlled aerial switches selected the correct unit for any particular transmission. A contemporary account states "This latest addition to the capacity of Ongar Radio Station will enable more and better services to be provided. Flexibility in use, in that any of the seven transmitters can he used to transmit any type of telegraph or picture transmission – they could equally well be used for telephony should this he required - and the saving in manpower by the almost complete automatising of the processes of operating and monitoring the transmitters are the keynotes to the
design"

However, by the mid 1960's, much of the equipment (apart from the ISB transmitters) was regarded as obsolete, and the station underwent
extensive modification. New transmitters, built and installed by Standard Telephones and Cables Ltd, were all controlled from the Central Control Position in "C" station and operated by one man.
Aerials changed too. There were nineteen beam aerials in 1952, but rising maintenance costs and demand for greater frequency flexibility resulted in their removal in 1966. They were replaced by the more versatile rhombic and log periodic aerials. Rhombic aerials grew from 20 in 1952, to 51 by the early 1970's. The original 1922 Marconi short wave aerials with their lattice masts and earth screens were still in use in 1952, but were removed over the next twenty years.

After the IRA Post Office Tower explosion in central London in 1971, the station was deemed to be a potential target and was surrounded by a security fence. This necessitated the diversion of the road to Ongar Park Farm to loop round the fence which enclosed the power house and cooling tank. Up to this time, local people were free to come and pick blackberries which grew well on the Redoubt!

The next major telecommunication revolution - satellite communication - resulted in the centralisation of services at Rugby and the closure of Ongar Radio Station on 31/10/1985. All masts were demolished soon after and all that can be seen today is a cellular telephone mast adjacent to "E" station. At the time of writing, all the buildings are derelict and badly vandalised, with part of the main transmitter hall at "C" station damaged by fire. The original Marconi buildings of "A" and "B" stations remain in splendid isolation almost exactly as built in 1922, and the original "C" station building of that period can be identified in the south west comer of the transmitter building complex, largely unaltered externally. "D" station is vanishing under scrub and brambles, but "E" station has been partly let and partly used for equipment in connection with the adjoining cellular telephone mast.

Attempts by the Post Office to obtain planning permission for 900 houses on the site were rejected by the planning authority, and the subsequent owners, London and Continental Developments, have applied for a variety of schemes including a hotel, golf courses, a business park and a holiday village as well as residential development. All have been refused. At present, there is discussion about the use of 13 acres for residential development, with the rest of the site remaining as Metropolitan Green Belt. It seems that all the radio station buildings may be demolished, though Essex County Council and English Heritage stated in 1966 that "some of the buildings may be worthy of retention owing to their historic interest".