RAF Bomber Command, “Y” Service (B.26 Group)

Peggy West

Early in the Second World War, during the Allied withdrawal from Europe and the beaches of Dunkirk, some radio enthusiasts in the United Kingdom stumbled upon important information. They realised that names of roads and towns, together with the estimated numbers of our troops and the routes they were taking in retreat, were being transmitted by the German Luftwaffe to their controllers on the ground. This led, in part, to German-speaking men and women like me being sought out. We were strictly vetted and invited to join something undefined and on “trust”, then sworn to the Official Secrets Act.

Volunteers who had moved to the United Kingdom from the occupied countries wore their Austrian, Czechoslovakian, Polish, Dutch, Belgian, Norwegian, Greek, and French “flashes” proudly on their shoulders. We were trained in wireless telegraphy to use Morse code and become known as W/T operators; we were also introduced to radio telegraphy with it’s use of plain-language intercepts, to become R/T operators, and then shown the intricacies of obtaining line bearings for use in Direction Finding Units, as part of D/F operations. After all that, we found to our surprise that we had become “Instant Sergeants”.

Arriving at Hollywood Manor in Kent, the RAF “Y” Service Headquarters, we learned of a network of highly secret radio stations and small direction finding units whose frequencies were tuned to the German Luftwaffe. These stations stretched from Montrose in Scotland down the east coast and round southern England to Strete in Devon. Inside the tightly secured radio intelligence sections, primarily German was spoken, thought, and written. Our reactions had to be those of the enemy.

Officially named RAF West Kingsdown, our headquarters was right in the middle of “bomb alley”, which later became the balloon barrage set to protect London. Unfortunately some RAF planes, or Luftwaffe ones with their bombs, and later those wretched doodlebugs, landed on or around us instead.

Thankfully my own “A” Watch was on duty the night an engine of a flying bomb did “cut-out” above us, blew up our men’s hut, and made a mess of the Watch room – but no radio links were lost. Our own WAAF hut was unsafe too and had to be knocked back into shape. Mind you, cleaning it was much easier after that; you just swept the dirt down the cracks of the foundations!

RAF West Kingsdown’s first admin officer was Miss Conan-Doyle, daughter of Sir Arthur. Wing Commander Budge, a wireless wizard, was our respected and dedicated commanding officer.

Initially the radios used were rather awkward boxes whose coil changes were needed at the most inappropriate times. They were HROs. But when small compact radio sets began to arrive from crashed German aircraft, or via clandestine routes, you can imagine we found those German sets were ideal for us too. These covered the whole spectrum of frequencies used by the Luftwaffe by rotation of one comfortable dial with precise tuning capabilities.

In addition, with the help of cable and wireless, the GPO, BBC and our own tower on nearby Wrotham Hill, the RAF developed high power transmitters that bounced signals off the ionosphere deep into Germany. Controlled by landline from Kingsdown, they made it possible for “Y” Service to start voice interference later in the war.

Much work in “Y” was intertwined with Britain’s Telecommunications Research Establishment, referred to as TRE, near Swanage. It was formally the Air Ministry Establishment at Bawdsey. Later TRE was relocated to Malvern to protect its developments when German shortwave experiments were detected across the English Channel near Cherbourg.

Our liaison with TRE meant that if important events were scheduled, Dr R.V. Jones or Dr Robert Cockburn came to give us insights into the technical measures, experiments, and countermeasures we needed to understand when listening for German reactions. Unfortunately, trusted with knowledge of those plans, when bad weather caused delays it would mean we were stuck in camp, cut off from the outside, from their visit onwards until completion of that operation.

So what were we faced with on the other side of the Channel?

Firstly, it was an enemy communicating mainly by codes. Codes ranged from the basic numerical through to sophisticated musical ones that redirected German aircraft to emergency landing grounds. All codes had to be detected and solved, locations established, and results mapped throughout the war.

Next, we found a system of regular patrols, each with their own ground station and squadron aircraft using individual tuning methods, call signs, code words, and little idiosyncrasies. Since all patrols altered frequencies together every fifth day, that individuality was just as well! Imagine bad weather and no flying for four days and then a flurry of late activity on the fifth with our frantic search to find and identify them all. Only for someone else to have to start the whole process again next morning. The Norwegian, Frisian, Dutch and Cherbourg lads are the ones I remember best. Searching for a code to the movement of those frequencies was time wasted. The selection was found to be totally random after the war!

Our systematic monitoring of all patrols did provide occasional grid references that helped the recovery of aircrew from the Channel or North Sea, and once I reported mention of two RAF bombs dropped inside Swiss Territory. That gave me quiet a bit of trouble – yes, I had heard the correct grid co-ordinates, and yes, I was sure! Trouble was, no one in the United Kingdom wanted to lay claim to those bombs! Weeks later I was very glad to see my CO’s friendly smile and hear, “Well done!” A protest had eventually arrived through “diplomatic channels”!

When bad weather stopped flying on both sides, it was fun to tune to the German E-boats chatting to each other off the east coast. Details of their last meals ashore made our mouths water; stories of their last hours spent with their women made our hair curl! But our “Y” Service D/F units fixed those positions and the Royal Navy stopped that danger from lurking close in-shore.

Other work was far more serious though:

Pictures of the Graf Spee with its telltale turret additions of Montevideo in 1939 had warned of German radar advances. In fact, eight radar installations were in place and operational on Heligoland, Sylt, Wangarooge, Borkum, and Nordeney by 1936.

Also, a German Long Range Early Warning System pinpointed UK departures 150 miles away. It was a 130 by 20-foot tower with rotating reflectors giving height, range, and bearings. Called the Wassermann, it was considered the best system overall during the Second World War.

Soon some important new developments were spotted: General Josef Kammhuber, in charge of German night-fighter operations, was establishing Germany’s first line of radar defences. Named the Kammhuber Line after himself, it was really a series of 20-mile wide “boxes” that contained two types of radar detection devices called the Freya and the Wurzburg. These so-called “boxes”, code-named "Himmelbett", were situated in a line near the coast from Denmark to the Swiss border, as well as further inland.

Several modifications over the years meant the Freya could eventually locate Allied planes two hundred miles away and track them to within seven miles. Freya had 360-degree coverage, but no altitude calculation, and operated on 107–158 megacycles.

The two Wurzburg sets inside each Himmelbett “box” were mobile and had a range from forty miles to two miles. The Wurzburg operated on 560 megacycles and aimed to take over an enemy plane from Freya – and then track it to the limit of it own range of two miles. One Wurzburg located the enemy plane; the second watched his fighter aircraft waiting in orbit over a “Little Screw” beacon. Ground Control then gave course of intercept. The Seeburg plotting table was used for that. Luckily for Bomber Command, this system proved slow and inferior to that used by the Allies.

The position of all enemy radar installations had to be re-confirmed throughout the war. Knowing the areas covered by German radar was vital to RAF route planning. For some time “Y” Monitoring Service had been hearing two new words, “Emil Emil”, used spasmodically with no indication of meaning or purpose. TRE needed reports urgently. For the first time in July 1942, a night fighter used the words “Emil Emil” together with a request for further vectors. Then, at last, two months later I heard a ground station asking his aircraft, “ Haven’t you picked up the enemy on your Emil Emil? You’ve been vectored to within two kilometres of it!”

Here was the answer; “Emil Emil” was an airborne radar extension. “Emil Emil”, the code name for Lichtenstein, was the last link in the German radar system!

Effective from two miles to within two hundred yards of an enemy aircraft, it operated on 490 megacycles – where we did not expect it – and was carried on the nose of Junkers 88s and Heinkel planes of the night-fighter squadrons. The Allies now knew that German radar cover extended from 200 miles to 200 yards.

Solving the puzzle of “Emil” was one of those valuable pieces of information obtained simply from a slip of the tongue or a security lapse by the enemy. Allied radar range at the time was 120 miles.

TRE was devising countermeasures to reduce losses caused by enemy radar installations and scientists needed to know what made the Wurzburg “tick” in order to find its antidote. In an exciting raid on Bruneval, the vital parts of one Wurzburg set were dismantled and taken back to England, together with two prisoners. By great good fortune, one of the prisoners was the operator of that Wurzburg installation!

TRE rebuilt the Wurzburg but experiments indicated electronic jamming would not be successful. Higher authority would have to be persuaded to sanction the use of metal strips, called “Window”. By coincidence, Germany and England had developed that system independently of each other and delayed its use for similar reasons: fear of the consequences if used in reverse.

I well remember that first Window-assisted Bomber Command raid. Boffins from TRE sat alongside R/T operators as we recorded the frustration and confusion those metal strips caused. The Wurzburg “fixes” were locked onto Window instead of aircraft and no amount of yelling “Rolf-Lise, Rolf-Lise” – right left wiggle waggle – could possibly produce any identification response from metal strips! It was utter chaos. The few diversionary Mosquitoes that dropped Window managed to hoodwink two hundred or more night fighters, who in their confusion collided with and attacked each other, got tangled in their own flack and colourfully lost their tempers!

Allied losses during those early Window-assisted raids were very low indeed.

TRE was also devising countermeasures against Freya and all ground-to-air communications. The first was “Moonshine”, which received pulses from Freya installations, amplified them and sent them back, producing the illusion of a force flying in formation, thereby drawing German fighters away from RAF attacks. In August 1942, 515 Squadron, flying old Defiant aircraft, conducted the first trials of Moonshine. Eight Defiants orbited near Portland. We listened as thirty German planes, the entire defence of Cherbourg, took to the air! A short while later those Defiants using Moonshine laid a “spoof” over the Thames that allowed US Flying Fortresses plus fighter escorts to attack Rouen. The Luftwaffe sent 144 planes to intercept the spoof but only a small number to Rouen.

“Mandrel” superseded Moonshine. Again, 515 Squadron Defiant aircraft were used to spread a screen of crude noise interference as they orbited fifty miles off and along the two hundred-mile length of the German coast. However, Mandrel’s effectiveness wore off and RAF losses rose again.

“Tinsel” and “Special Tinsel” followed. They were more effective and were used to the end of the war. With these, RAF wireless operators simply relayed the noise of the engines to swamp Luftwaffe ground-to-air communication. With Special Tinsel, “Y” measured a frequency, passed it to the RAF wireless operator, thereby ensuring he tuned to the traffic we needed to negate. Tinsel had an immediate impact on RAF losses.

For us, the number of “safe returns” appeared for the first time on our Operations board at Kingsdown, and thankfully because this was, after all, the only contact we had with normality. It was the reason why we operated for so many hours in the world of the enemy. You have no idea how much the simple phrase, “You are our eyes and ears inside Germany” meant when said by experts from TRE to help us through some difficult periods.

Early in 1943, “Airborne Cigar”, or ABC, was introduced to further disrupt radio communication. An extra crewmember, plus his equipment, had to be squashed inside some Lancaster planes of 101 Squadron. My husband, a Lancaster pilot, knew them as “Specials”. We knew of them – German-speaking volunteers.

Max Doolette from Adelaide was Jacks “Special”. Max would have found and jammed operational frequencies using a 3” diameter cathode-ray tube. Hide-and-seek developed over the band with the Luftwaffe operator moving his transmission to clear space; the Special on board the Lancaster following him; we Kingsdown operators and the German ground station trying to follow them both – as well as each other. It all got a bit hectic!

Then in October 1943 something quite different was introduced – “Corona”. At Kingsdown, using those high power transmitters to reach far into enemy country, specially selected men and women began annoying voice interference on the 3–6 megacycle range. Pseudo controllers issued false tuning counts to prevent the Luftwaffe going operational, gave false fog warnings to get aircraft to land, read poetry, or relayed Hitler’s speeches to disrupt and frustrate, and gave direct, contrary orders to cause confusion.

Corona led to some amusing incidents. A German controller was trying to direct his aircraft to Kassel. Kingsdown’s “ghost” was trying to stop them and told them not to take any notice of the Englander who was trying to confuse them. After an exchange or two, the German became pretty agitated, lost his temper, and swore. Our “ghost” replied, “The Englander is now swearing” and was met by an infuriated shriek from Germany: “Its not the blank Englander who is swearing, its blankety-blank me”!

When a 101 Squadron Lancaster with its ABC “Special” was shot down over Berlin, the Luftwaffe assumed Kingsdown’s “Corona” voice interference came from that ABC equipment. They reasoned, correctly, that the RAF would not allow women to fly operationally over Germany and switched to women ground controllers. Since we had anticipated that, we did the same.

One of our girls got into a similar battle of wills, the only difference being that both women ended up laughing with each other and had to shut down. We all enjoyed the incident very much – but did wonder what happened to the lass over there!

There is so much more to the story of “Y” Service and its intercepts. The mass of information we gathered – personal, technical, structural, and operational – was pieced together elsewhere. It was great when specialists came to show us results.

Although all R/T operators qualified in Morse, that was left mainly to our W/T specialist men operators, who coped stoically for hours on end at the rear of the watch room. Their work, combined with information from us, was sent to Bletchley and other specialist sections. We received their “Most Secret” printouts in return.

In effect, we were encouraged that signals can be heard because instructions had to be given; bearings can be taken and fixes can be obtained. Then photo-reconnaissance can be called to pinpoint and the problem dealt with.

RAF “Y” Service was recognised for its work that resulted in the destruction of enemy radar. By D-Day, only 16 of the 92 Himmelbett stations were operational at all, and all Wassermann long-range sets had been destroyed.


[†] The HRO was a technically sophisticated radio receiver developed during the mid-1930s. The design allowed a range of frequencies to be searched, and the tuning was very precise. The HRO could effectively receive both Morse and voice transmissions, and it was widely used by Allied forces, both for communication and for monitoring enemy radio traffic. (Ed.)

Peggy West was born in the United Kingdom in 1922 and spent part of her childhood in Germany where her father was a manufacturer. When war came, she volunteered for what became known as the “Y service”, Bomber Command’s network of secret radio and direction finding stations tuned to the Luftwaffe that stretched from Montrose in Scotland, down the East Coast round Kent and Hampshire to Devon. After the war she trained as a teacher and taught in England, Southern Rhodesia and Ghana. With her husband Jack and son Robert she farmed in New Zealand for a number of years before arriving in Australia in 1986.