Taylor and I divided up the technical work. The Post Office pressed ahead with research into infrared detection. I began using the resources of the Services Electronics Research Laboratory to develop new microphones and look into ways of getting sound reflections from office furniture. I was already familiar with the technical principles of resonance from my antisubmarine work. When sound waves impact with a taut surface such as a window or a filing cabinet, thousands of harmonics are created. The knack is to detect the point at which there is minimum distortion so that the sound waves can be picked up as intelligible speech.
One day in 1951 I received a telephone call from Taylor. He sounded distinctly agitated.
"We've been beaten to it," he said breathlessly. "Can we meet this afternoon?"
I met him later that day on a park bench opposite the Foreign Office. He described how one of the diplomats in our Embassy in Moscow had been listening to the WHF receiver in his office which he used to monitor Russian military aircraft traffic. Suddenly he heard the British Air Attache coming over his receiver loud and clear. Realizing the. Attache was being bugged in some way, he promptly reported the matter. Taylor and I discussed what type of microphone might be involved and he arranged for a Diplomatic Wireless Service engineer named Don Bailey to investigate. I briefed Bailey before he left for Moscow on how best to detect the device. For the first time I began to realize just how bereft British Intelligence was of technical expertise. They did not even possess the correct instruments, and I had to lend Bailey my own. A thorough search was made of the Embassy but nothing was ever found. The Russians had clearly been warned and turned the device off.
From questioning Bailey on his return it was clear to me that this was not a normal radio microphone, as there were strong radio signals which were plain carriers present when the device was operating. I speculated that the Russians, like us, were experimenting with some kind of resonance device. Within six months I was proved right. Taylor summoned me down to St. James's Park for another urgent meeting.
He told me that the U. S. State Department sweepers had been routinely "sanitizing" the American Ambassador's office in Moscow in preparation for a visit by the U.S. Secretary of State. They used a standard tunable signal generator to generate what is known as the "howl round effect,'' similar to the noise made when a radio station talks to someone on the telephone while his home radio or television is switched on. The "howl round" detected a small device lodged in the Great Seal of the United States on the wall behind the Ambassador's desk.
The howl frequency was 1800 MH, and the Americans had assumed that the operating frequency for the device must be the same. But tests showed that the device was unstable and insensitive when operating at this frequency. In desperation the Americans turned to the British for help in solving the riddle of how "the Thing," as it was called, worked.
Brundrett arranged for me to have a new, secure laboratory in a field at Great Baddow, and the Thing was solemnly brought up by Taylor and two Americans. The device was wrapped in cotton wool inside a small wooden box that looked as if it had once held chess pieces. It was about eight inches long, with an aerial on top which fed into a cavity. Inside the cavity was a metal mushroom with a flat top which could be adjusted to give it a variable capacity. Behind the mushroom was a thin gossamer diaphragm, to receive the speech, which appeared to have been pierced. The Americans sheepishly explained that one of their scientists had accidentally put his finger through it.
The crisis could not have come at a worse time for me. The antisubmarine-detection system was approaching its crucial trials and demanded long hours of attention. But every night and each weekend I made my way across the fields at the back of the Marconi building to my deserted Nissen hut. I worked flat out for ten weeks to solve the mystery.
First I had to repair the diaphragm. The Thing bore the hallmarks of a piece of equipment which the Russians had rushed into service, presumably to ensure it was installed before the Secretary of State's visit. They clearly had some kind of microscopic jig to install the diaphragm, because each time I used tweezers the thin film tore. Eventually, through trial and error, I managed to lay the diaphragm on first and clamp it on afterward. It wasn't perfect, but it worked.
Next I measured the length of the aerial to try to gauge the way it resonated. It did appear that 1800 MH was the correct frequency. But when I set the device up and made noises at it with an audio-signal generator, it was just as the Americans had described - impossible to tune effectively. But after four weekends I realized that we had all been thinking about the Thing upside down. We had all assumed that the metal plate needed to be opened right out to increase resonance, when in fact the closer the plate was to the mushroom the greater the sensitivity. I tightened the plate right up and tuned the radiating signal down to 800 megacycles. The Thing began to emit a high-pitched tone. I rang my father up in a state of great excitement.
"I've got the Thing working!"
"I know," he said, "and the howl is breaking my eardrums!"
I arranged to demonstrate the Thing to Taylor, and he traveled up with Colonel Cumming, Hugh Winterborn and the two American sweepers. My father came along too, bringing another self-taught Marconi scientist named R J Kemp, who was now their Head of Research. I had installed the device against the far wall of the hut and rigged up another monitor in an adjoining room so that the sounds of the audio generator could be heard as if operationally.
I tuned the dials to 800 and began to explain the mystery. The Americans looked aghast at the simplicity of it all. Cumming and Winterborn were smug. This was just after the calamity of the Burgess and Maclean affair. The defection to the Soviet Union of these two well born Foreign Office diplomats in 1951 caused outrage in the USA, and any small way in which British superiority could be demonstrated was, I soon realized, of crucial importance to them. Kemp was very flattering, rightly judging that it would only be a matter of time before Marconi got a contract to develop one themselves.
"How soon can we use one?'" asked Cumming.
Kemp and I explained that it would probably take at least a year to produce equipment which would work reliably.
"I should think we can provide the premises, Malcolm," said Kemp to Cumming, "and probably one man to work under Peter. That might get you the prototype, but after that you'll have to get funding."
"Well, it's quite impossible for us to pay, as you know," replied Cumming. "The Treasury will never agree to expand the secret vote."
Kemp raised his eyebrows. This was obviously an argument Cumming had deployed many times before in order to get facilities for nothing.
"But surely," I ventured, "if the government are serious about developing things technically for MI5 and MI6 they will have to allocate money on an open vote."
"They're most reluctant to do that," replied Gumming, shaking his head. "As you know, we don't really exist."