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Aspidistra: The wartime breakthrough you’ve never heard of

Posted by: , Posted on: - Categories: FCO Services, Second World War

How Britain built the most powerful radio transmitter in the world, and gave Goebbels ‘something to worry about'.

The entrance going into a large tunnel, with the tall Aspidistra on top.
Crowborough, the site of Aspidistra, as it is today Source: Nick Catford, Subterranea Britannica

The powerful weapon

On 16 May 1941, the Prime Minister, Winston Churchill, heard about a new, powerful weapon. Immediately seeing its potential, he encouraged its development. He knew this weapon could cause huge damage and yet it did not use bullets or explosions; it used words.

The weapon was “Black Propaganda” – creating enemy propaganda that Germans would think was German. This type of propaganda is very believable and therefore is more likely to convince the enemy. The easiest way of delivering these messages was radio, but there was a problem. The radio signal needed to be strong enough to look like it came from Germany. To create such a strong signal, the radio transmitter had to be incredibly powerful.

Building a Revolutionary Transmitter

The task of finding such a radio transmitter fell to the Special Communication Unit VIII, a predecessor of FCO Services. Harold K Robin, the chief engineer, had the job of making the weapon a reality.

It so happened that the Radio Corporation of America (RCA) had created two high powered radio transmitters. However, a change in the law meant they could not be used in the USA, so the RCA were eager to sell them to Britain. Harold saw their potential, and travelled to America to work with the RCA to improve the radio transmitters.

These improvements made the transmitters unique. Originally consisting of two 200 KW transmitters, Harold and the RCA developed it to become one, with 600 KW. To put it in perspective, most transmitters at the time were 25-150 KW, and the new transmitter could be “split” into multiple smaller units. This made it the most powerful medium wave radio transmitter in the world at the time.

The improved transmitters were named Aspidistra, referencing the popular Gracie Fields song ‘The Biggest Aspidistra in the World’. Aspidistras used to be popular house plants that were fairly short, but the song describes how one grows until it ‘nearly reached the sky’.

The thing that made Aspidistra really impressive, however, was how easy it was to tune. Back then it usually took several hours to change the frequency of a transmitter, as technicians had to rearrange crystals. Harold made Aspidistra able to move frequency in a fraction of a second, the same way you change channels on a car radio. This meant Aspidistra could do more, and it was harder for the Germans to stop it.

Perfecting Aspidistra wasn’t the end of Harold’s work. Transporting the aerial and transmitter meant sailing them across the U-boat infested Atlantic Ocean. And whilst the transmitter arrived safely, the ship carrying the aerial was torpedoed and the aerial had to be rebuilt.

Harold did have some luck in constructing the site at Crowborough. The Canadian government generously loaned a team of Canadian engineers nearby, with no other pressing duties, for the work.

Black and white picture of aerials above trees
Aspidistra’s aerial array, on site at Crowborough

 A ‘very good job of propaganda’

The British used Aspidistra during the Second World War for several operations. It would take several articles to do justice to them all, but two of the most important were Soldatensender Calais and Operation Dartboard.

Soldatensender Calais

Soldatensender Calais pretended to be a radio station for German soldiers, broadcasting jazz music interspersed with news bulletins. Information from spy networks kept the news as accurate as possible, so that listeners trusted the station. However, all news was presented as negatively as possible to destroy the morale of the listeners.

This station was so successful, it received high praise from the master of propaganda himself: Joseph Goebbels.

In the evening the so-called “Soldatensender Calais” which evidently originates in England and uses the same wavelengths at Radio Deutschland – when the latter is out during air raids – gave us something to worry about. The station does a very good job of propaganda, and from what is put on the air one can gather that the English know exactly what they have destroyed in Berlin and what they have not.

28 November 1943, Dr Joseph Goebbels[1]

Operation Dartboard

Because Aspidistra could change frequency quickly, it could impersonate German ground control. Fluent German speakers gave false information to German pilots, redirecting them away from Allied bomber attacks. Every time the Germans tried to make ground control harder to impersonate, the British adapted. For example, when German ground control started using female controllers, the British followed suit.

Not grabbing the headlines, the role of Aspidistra is mostly forgotten. Yet it caused disruption and confusion across Germany, and was a marvel of engineering.

After the War


Men maintaining equipment
Maintenance of the generators at Crowborough after World War Two

At the end of the Second World War, the BBC took control of Aspidistra. It was clear that Aspidistra was the perfect transmitter for the new BBC World Service. It could reach far across Europe, and its ability to change frequencies meant it could deliver local programs in different countries.

The predecessors of FCO Services continued to maintain Aspidistra, supplying the technology, staff and locations for the BBC World Service to broadcast around the world. Finally, in 1984, the Government gave the funding for the World Service directly to the BBC, and they became responsible for maintaining their aerials worldwide.

The site in Crowborough still exists, but today Sussex police use it for training purposes. FCO Services is stronger than ever, and whilst they have evolved into producing security services, to this day they still develop cutting edge technology.

[1] Joseph Goebbels, The Goebbels Diaries: 1942-1943. trans. Louis P. Lochner (Garden City: Doubleday, 1948).

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  1. Comment by Jonathan Paul Marks posted on

    Hello Katherine. Thank you for writing such a fitting tribute to the work of Harold Robin. I made three radio programmes with him which are now on line. Two are about his work during the war.
    the third was about his work during Rhodesian UDI.

    His work is also mentioned in this video about Orfordness.

    Perhaps you can add these links to your article.

  2. Comment by Graham Evans posted on

    Have just read ‘Radio Warfare from Sussex’ by Roy Bliss. This describes Aspidistra and much else including ‘Black’ radio psy-ops, much coordinated by Sefton Delmer.