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Gilnahirk's Best Kept Secret

by benvista

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Contributed by 
benvista
People in story: 
To the memory of Capt Joe Banham, Y Service
Location of story: 
Gilnahirk, County Down, Northern Ireland
Background to story: 
Army
Article ID: 
A8533811
Contributed on: 
14 January 2006

This is St Erth's radio room at the end of the war. Gilnahirk would have had a similar set up. Note the American HRO receivers.

The information contained in this story is based on the accounts of Gilnahirk people who can remember the early days of the Radio Station. I shall also draw on the accounts of the Y Service which have appeared in some recent books.

Sometime in the late 1930’s a government building and its infrastructure arrived among the farms and green pastures which make up the town land of Ballyhanwood. It was one of those places which everyone in the local area was aware of, but that was it. From the beginning the Radio Station has been associated with all sorts of rumours and wild tales. This account will reveal only part of the true story about the role played during the second world war. The fine detail is still locked up in top secret government files, sixty years after the event.

The article is dedicated to the memory of Captain Joe Banham the officer in charge at Gilnahirk during the war years. We remember also the men and woman who worked at Gilnahirk, but their names remain a mystery to this day, because those who worked at this location never talked about their work, neither during nor after the war. It was a part of our WWII history that each and every one of them took to their graves.

During the run up to WWII the G.P.O. established a radio station on the Castlereagh Hills overlooking Belfast. The site consisted of a few wooden and nissan huts which were surrounded by a considerable number of very tall telegraph poles dotted about the adjoining fields. These poles were linked together with overhead wire and formed the aerial network which was used to intercept the radio traffic of the time. The wooden huts served a number of roles, but one hut would have contained the main radio room. This consisted of eighteen banks of American HRO radio receivers. These receivers were the Rolls Royce of their day and no signal escaped the fine tuning of an HRO receiver. During the establishment of this station a Top Secret Marconi-Adcock Direction finding facility was placed into an all metal tank and then the whole thing was buried just below the ground some distance from the main collection of wooden huts. Four thirty feet high telegraph poles were placed one at each corner of this underground structure.

All this work was carried out by the Royal Corps of Signals and the G.P.O. radio department. The Belfast electricity company supplied a transformer to the site, but the main cable feed for that transformer had to be buried below the ground incase it caused any interference to the signal reception. The G.P.O. also provided an underground high grade telephone cable which allowed the station to be part of a much bigger wartime communications network.

Local farmers supplied the radio station with milk and vegetables. On Sunday mornings the off duty soilders were marched down the road to Gilnahirk Presbyterian Church. Before the Belfast Blitz most if not all the radio operators lived in military accomodation within the city. After the Blitz, a local farmer was asked to convert a big wooden chicken house into a barrack block for most of the operators. The remainder boarded with local people in the Gilnahirk area. Through time additional nissan huts were added to the site along with a NAAFI. The local bus service to Manns Corner had been around for some years, but with the coming of radio station the timetable was adjusted to fit the needs of the station. As the war progressed wooden poles were replaced with steel radio masts, and older out of date equipment was continually updated.

So what was it all about:

The radio signal was the internet of the war. It allowed people, military units and governments departments to keep in touch when they were traveling. The G.P.O. were the guardians of this technology and under an act of parliament they had to police the air waves. Anyone caught operating a radio set without approval was up to no good and it was the job of the G.P.O. to put them out of business. When Gilnahirk was officially switched on it had the ability to listen in on all radio transmission, and it also had the ability with the assistance of one or two other locations within the United Kingdom to locate the position of that transmission.

The Coming of War and the Outbreak of War.

The government of the day believed that Germany and her allies would send secret agents into the kingdom to spy and report back on the various aspects of our wartime planning. When all this started there was a serious lack of trained radio operators to listen in on the many frequencies available to the enemy. To assist in this mammoth task the government secretly selected and recruited hundreds of amateur radio enthusiasts to listen in on given frequencies. Here in Northern Ireland our amateurs had their part to play, and every transmission they heard was recorded on paper logs giving the date, the time, the frequency, and the message. These amateurs were known as the Radio Security Service or R.S.S. for short. Sometimes only part of a message was received, but everything was recorded and sent to PO Box 25, Barent. Please remember that each of these amateurs had signed the official secrets act and most if not all in Northern Ireland have gone to their graves without revealing their secret wartime role. It was drummed into them that they must never every talk about there work, not even to family or other radio amateurs.

At PO Box 25 all these reports were cross referenced and checked. Part of a message which was missed by a listener in Scotland may well have been heard by someone in Southhampton, the Isle of Man or County Down. It was just like putting a jigsaw together, a piece here and a piece there, but over time a picture began to emerge of what was going on. If something of interest or importance to our war effort appeared it was handed over to the professionals. Bring Gilnahirk and other such locations unto the field of battle. The frequency of special interest message was passed on to a fulltime operator. He tuned his HRO set and waited. Please understand that we are not listening to a constant stream of information. This was a twenty four seven watch and there may have been hours even days when northing was heard, but our operator had to be ready when suddenly without warning that frequency came to life with the tapping of a Morse key.

All the messages which were heard and recorded by both the amateurs and professionals were simply a jumble of letters. Normally sent in groups of five letters. This was not a message in plain readable text. It was encoded so that only the sender and the official receiver would have known the key to breaking the code and reading the text of the message. We now bring two very familiar wartime names into our story, “Bletchley Park” and “Enigma.” The work of Gilnahirk which had started modestly under the control of the G.P.O. was now in the realms of MI6 and was part of Special Communication Unit Three. The first military guards around the site were the Inniskillings and The Royal Ulster Rifles, but by 7 February 1942 the Blue Caps of the Royal Military Police were in charge and everything at the Radio Station was air tight. The building and its content were considered a vulnerable point and had become one of the most secure and secret places in the nation.

The fine details of what Gilanhirk actually did are still locked away in top secret government files and this current generation may never read what went on. It is true to say that even the people who worked at Gilnahirk did not know what they were doing; such was the way in which our intelligence organization worked. The information of a Secret, Top Secret, and Ultra Secret nature would have been known to only a very few individuals. It was the old rule of, “A Need to Know.”

In concluding the story of Gilnahirk’s wartime role I will give a considered example of the war against Hitler. The Battle of the Atlantic was on our doorstep with Glasgow, Liverpool, Belfast and Londonderry ready to send or receive our merchant navy convoys. A member of the Radio Security Service picks up part of a U-Boat message looking for a convoy. This frequency has now been passed on to Gilnahirk and is monitored around the clock. Days pass and nothing more is heard, but suddenly and without warning another message is overheard by the HRO set operator who has been patiently waiting. At this point he does a number of very important things.

1. He starts to write the message down, letter by letter.
2. At the same time he alerts his controller, who will also listen in and make a copy.
3. And finally he sends the very same radio signal down a telephone line to Beaumanor central control in England.

I spoke earlier of the Adcock Direction Finding equipment at Gilnahirk. This was also manned twenty four seven just like the rest of the site. The difference, you were sitting in a metal tank, just below the surface of the ground on your own for eight hours. Once again hours and days may have passed with nothing to do but wait.

Suddenly Beaumanor alerts you to the task in hand. The signal frequency which has been received just yards away in the wooden hut down the field, is now coming to you over a telephone line via England and you can hear it loud and clear in the right hand ear piece of your headset. As quickly as you can, you begin to hunt for the same signal using a Goiniometer and a HRO receiver. Within seconds you hear the signal loud and clear in your left hand ear piece of your headset. Bingo! You read off the compass bearing from the dial in front of you. Using a Morse key you send the bearing reading back to Beaumanor on a second dedicated telephone line. So quick and skilled were the D/F operators that it took them only seconds to get a bearing on the transmission.

This Direction Finding task would also have been carried out at the same time in other locations within the UK. By sending the signal via a telephone line from Gilnahirk to Beaumanor, it is possible to send the same signal back to Gilnahirk on a separate telephone line, and on to other D/F sites an the same time. With the bearing readings of two or more D/F sites we can very quickly pinpoint the location of the transmission on a very large map in the Beaumanor plotting room. Our U-Boat is now on the map, and if possible we will keep our convoys well away from him, and at the same time track his movements from further radio transmissions. His radio transmissions will in turn reveal other U-Boats and support vessels in the Atlantic. Over time a complete picture of who is in the Atlantic is on our map. We know the type of U-Boats, their speed, their range, and if we loose contact we can still guess where they might be. In time the hunter becomes the hunted and is finally destroyed. The radio opeator on a U-Boat would have a set way in which he sends his message. This is called a finger print. A good operator at Gilnahirk can tell if he is listening to the same German operator even though the frequency may have changed.
This is just one example of the important role a few huts, a collection of telegraph poles and a metal tank in the town land of Ballyhanwood played in the war against Hitler. I am sure many of the soldiers of the Inniskillings and Royal Ulster Rifles who stood guard on cold, wet and windy nights at Gilnahirk never realized that they were indeed on the front line in our Nations efforts to beat Hitler and win the Second World War. The wartime site is gone and the town land of Ballyhanwood has returned to green pastures. Churchill said that Bletchley Park was the Goose that laid the golden eggs. In submitting this article I want it remembered that is was the RSS and places like Gilnahirk who fed the Goose and gave her the ability to lay the golden eggs.

The author would like to thank Bob King a former member of the RSS for his assistance in making this story possible. January 06

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