It was a long shot, but it had to be at least a possibility that Courtney Young's illegal was the same person who was receiving the GRUFF signal from Moscow. The Radiations Operations Committee searched the Clapham area intensively for any further clues. We drove our radio-transparent RAFTER van over to Clapham, and made a base in the walled forecourt of the old air raid shelter which ran under the south side of Clapham Common. We took power from inside the shelter, and rigged up an aerial which I estimated would give us a range of about half a mile.
I sat with Tony Sale in the cold, poorly ventilated van, watching, waiting, listening. The GRUFF broadcast was due at 10 A.M., so we tuned our first receiver to GRUFF, and searched the nearby frequencies with our other receiver to see if we could detect any oscillator. In the second week, we got a "hit," a strange, owl-like hoot, modulated with the Morse from Moscow. Someone was listening to the GRUFF broadcast within half a mile of us. Tony Sale looked across at me, momentarily, the scent of prey in his nostrils. The tape recorders began to roll with a subdued click. We switched to battery power supply, and drove slowly down Clapham High Street toward the tube station, weaving our way through the traffic. The pubs were full. Daffodils were just appearing in the neat front gardens of the suburban houses along our route, those inside oblivious of the chase passing in front of their doors.
Tony Sale was monitoring the local oscillator signal, using its strength as a guide to its location. We knew GRUFF stayed up in the air for twenty minutes. We had seventeen left. As we reached the tube station the signal became fainter, so we doubled back toward Wandsworth, but again the signal dropped away. We went south, toward Balham, but this time the signal disappeared before we even left the Common.
There were six minutes to go. Barely a word had been spoken inside the van. We only had one direction left. GRUFF had to be sitting up to the north, somewhere in the crowded maze of Battersea back streets. Our special van lumbered into Latchmere Road. Frustration welled up inside me. I wanted to career around the corners, shout out for help through a loud hailer, set up roadblocks. All we could do was stare at the flickering dials, willing them to move up, and not down. But by the time we crossed Wandsworth Road the signal was already trailing away, and shortly after that, Moscow signed off, GRUFF was gone. Tony Sale thumped the side of the van. I tore my headphones off, feeling drained and angry. How many more months might we sit in Clapham before we got as close again?
I lit my thirteenth cigarette of the day and tried to make sense of the previous twenty minutes. We had traveled in every direction. But the fact that the local oscillator signal got weaker each time we moved, proved beyond any doubt that we had genuinely detected another receiver besides our own. But it was located neither to the north nor south, not to east or west. Slowly the awful truth dawned on me. GRUFF must have been right on top of us, listening within yards of the air raid shelter. We drove back to our base, and searched the area. Behind a high wall at the back of us was a large wasteland car park. GRUFF must have been parked there in a car, or perhaps a van like ours.
Back at Leconfield House I printed out the tape recordings of the local oscillator on a sonargram. The sound waves modulated with a small mains ripple. But the wave form was not at mains frequency. It was similar to that produced by battery power packs used in cars and vans to produce alternating current. The coincidence was almost too painful to contemplate.
For the next six months the Radiations Operations Committee flooded Clapham with every spare man at our disposal. We listened in hundreds of locations. Officers scrutinized every street, searching for signs of a telltale aerial. Discreet inquiries were made of radio equipment suppliers. But all to no avail. And every Tuesday and Thursday night the GRUFF signal came through the ether from Moscow, mocking us as we searched.
As well as mobile RAFTER, we began, through ROC, to arrange airborne RAFTER. An RAF transport plane equipped with receivers similar to those in the van made regular sweeps across London. We thought that with the extra height we would be able to get a general idea of where receivers were operating in London. Then, having located a signal to a specific area, we could flood it with mobile RAFTER vans.
We spent our first flight over the Soviet Embassy to check our equipment was working, and picked up their receivers immediately. We got a series of radio hits in the Finsbury Park area, and we flooded the locality, as we had in Clapham. But, like GRUFF, the agent remained undetected, comfortably camouflaged in the dense undergrowth of London's suburbs.
The RAFTER plane flights were a kind of agony. I spent night after night up in the indigo sky, listening to the signals coming in from Moscow, insulated from the deafening sound of the plane's propellers by headphones. Down below, somewhere amid the endless blinking lights of London, a spy was up in an attic, or out in a car, listening too. I knew it. I could hear him. But I had no way of knowing where he was, who he was, whether he worked alone or as part of a ring, and, most important of all, what Moscow was telling him. I was caught between knowledge and the unknown, in that special purgatory inhabited by counterespionage officers.
But although the RAFTER side did not immediately bear fruit, the ENGULF side, using technical means to break ciphers, soon proved enormously successful. Things really took off with a meeting in Cheltenham chaired by the GCHQ Assistant Director of Research, Josh Cooper, in 1957. Cooper realized the need for close coordination between all three Services if the new breakthrough was going to lead to further cipher-breaking success. He brought together for the first time the various interested parties - Hugh Alexander and Hugh Denham from GCHQ's H Division (Cryptanalysis); John Storer, the head of GCHQ's Scientific section responsible for Counter Clan in M Division; and Ray Frawley, me, and my opposite number in MI6, Pat O'Hanlon.
Apart from the Russians, the Egyptians still remained GCHQ's first priority. They used Hagelin machines in all their embassies, split into four groups, each group containing different cipher wheel settings. Providing we could get a break into any one machine, every machine in that group would be vulnerable. If we could obtain samples of any one machine, every machine in that group would be vulnerable. MI6 and GCHQ drew up a list of the Egyptian embassies worldwide, along with details of which machine group they belonged to. The committee then evaluated which embassy in each group presented the best possibility for a successful ENGULF operation, and I briefed the MI6 teams on how to plan the operations. Within a year we had broken into every Egyptian cipher group.
Although ENGULF made all classes of Hagelin machines vulnerable, these tended to be the preserve of Third World countries. Cooper hoped, by calling his meeting, to find ways of applying the ENGULF principles to more advanced cipher machines, which GCHQ lacked the computer power to attack. My approach was simple; we had to put operations into practice even if, on paper, they looked unlikely to yield results.
"We've got to approach the problem scientifically," I said, "We don't know how far we can push these new breakthroughs, so we have to experiment. Even if things go wrong, we'll still learn things we didn't know before."