We all laughed.
Leslie was always most mysterious about the source of his expert knowledge on lockpicking, but for years I carried a piece of wire and stroking tool that he made for me.
"Make sure you carry your police pass," he told me when he first gave it to me, pointing out that I was, technically, breaking the law by going about equipped for burglary.
"Couldn't be thought of as common or garden burglars, could we?"
He laughed heartily and strode back to the Dungeons.
A few days after the lockpicking class I went on my first operation.
"The Third Man business is brewing up again," said Hugh Winterborn. "MI6 are interrogating one of their officers - chap named Philby. They want us to provide the microphone."
I had met Kim Philby briefly on my first visit to Leconfield House in 1949. I was in Cumming's office discussing the work for Brundrett when Philby popped his head around the door. He immediately apologized for disturbing us.
"No, come in, Kim," said Cumming in his usual gushing way. "There's someone you ought to meet."
Cumming explained that I had just been appointed the External Scientific Adviser. Philby shook my hand warmly. He had a lined face, but still looked youthful.
"Ah, yes," he said, "that's Brundrett's committee. The Americans are very keen on that, I gather."
I took to Philby immediately. He had charm and style, and we both shared the same affliction - a chronic stutter. He had just been appointed MI6 Head of Station in Washington, and was saying goodbye to his friends in MI5 and getting various briefings from them before his departure. Philby had developed close links with MI5 during the war, one of the few MI6 officers to take the trouble. At the time the visit seemed typical of Philby's industriousness. Only later did the real reason become clear. Philby quizzed me on my thinking about science. I explained that the Intelligence Services had to start treating the Russians as a scientist would treat the subject - as a phenomenon to be studied by means of experiments.
"The more you experiment, the more you learn, even if things go wrong," I said.
"But what about resources?" asked Philby.
I argued that the war had shown scientists could help solve intelligence problems without necessarily needing a huge amount of new apparatus. Some was needed, certainly, but more important was to use the materials already available in modified ways.
"Take Operational Research," I said, referring to the first antisubmarine-research program in the Navy during the war. "That made a tremendous difference, but all we scientists did was to use the gear the Navy had more efficiently."
Philby seemed skeptical, but said that he would bear my thoughts in mind when he reviewed American thinking on the subject on his arrival in Washington.
"I'll look you up when I get back," he said. "See how you've got on." He smiled graciously and was gone.
Two years later, Burgess and Maclean defected. It was a while before Cumming mentioned the subject, but by 1954 I had gathered enough snippets from him and Winterborn to realize that Philby was considered the prime suspect for the Third Man who had tipped off the two defectors. In 1955 he was sacked by a reluctant MI6, even though he admitted nothing. On September 23, 1955, three weeks after I formally joined MI5, the long-awaited White Paper on the Burgess and Maclean affair was finally released. The press savaged it. Philby's name was well known in Fleet Street by this time, and it was obviously only a matter of time before it was debated publicly.
In October, MI5 and MI6 were informed that the question of the Third Man was likely to be raised in the House of Commons when it reconvened after the recess, and that the Foreign Secretary would have to make a statement about Philby's situation. MI6 was ordered to write a review of the case, and called in Philby for another interrogation. They, in turn, asked MI5's A2 section to provide recording facilities for the interrogation.
Winterborn and I took a taxi to the MI6 safe house near Sloane Square where Philby was due to meet his interrogators. The room MI6 had chosen was sparsely furnished - just a patterned sofa and chairs surrounding a small table. Along one wall was an ancient sideboard with a telephone on top.
As it was important to get as high a quality of recording as possible, we decided to use a high-quality BBC microphone. Speech from a telephone microphone is not very good unless it is high level. We lifted a floorboard alongside the fireplace on the side on which Philby would sit and inserted the microphone beneath it. We arranged an amplifier to feed the microphone signal to a telephone pair with which the Post Office had arranged to feed the signal back to Leconfield House.
The Transcription Center was hidden behind an unmarked door at the other end of the corridor from the MI5 staff canteen and only selected officers were allowed access. Next to the door were a bell and a metal grille. Hugh Winterborn identified himself and the automatic lock clattered open. Directly opposite the entry door was a door giving entrance to a large square room in which all the recording was done by Post Office employees. When the material was recorded, the Post Office could hand it over to the MI5 transcribers, but it was illegal to let MI5 monitor the live Post Office lines (although on occasion they were monitored, particularly by Winterborn or me, if there was something causing difficulties or very important). The telephone intercepts were recorded on dictaphone cylinders and the microphone circuits were recorded on acetate gramophone disks. This room was MI5's Tower of Babel. The recordings were handed over to women who transcribed them in small rooms running along a central corridor.
The Department was run by Evelyn Grist, a formidable woman who had been with MI5 almost from the beginning. She had a fanatic devotion to Vernon Kell, and still talked darkly of the damage Churchill had done to the Service by sacking him in 1940. In her eyes, the path of Intelligence had been downhill ever since.
Hugh Winterborn arranged for the link to be relayed into a closed room at the far end. We sat down and waited for the interrogation to start. In fact, to call it an interrogation would be a travesty. It was an in-house MI6 interview. Philby entered and was greeted in a friendly way by three former colleagues who knew him well. They took him gently over familiar ground. First his Communist past, then his MI6 career and his friendship with Guy Burgess. Philby stuttered and stammered, and protested his innocence. But listening to the disembodied voices, the lies seemed so clear. Whenever Philby floundered, one or another of his questioners guided him to an acceptable answer.
"Well, I suppose such and such could be an explanation."
Philby would gratefully agree and the interview would move on. When the pattern became clear, Winterborn fetched Cumming, who strode into the office with a face like thunder. He listened for a few moments, slapping his thigh. "The buggers are going to clear him!" he muttered. Cumming promptly sent a minute to Graham Mitchell, the Head of MI5 Counterespionage, giving an uncharacteristically blunt assessment of the MI6 whitewash. But it did no good. Days later, Macmillan got up in the House of Commons and cleared him. I realized for the first time that I had joined the Looking-Glass world, where simple but unpalatable truths were wished away. It was a pattern which was to be repeated time and time again over the next twenty years.
The Philby interview gave me my first experience of the MI5 surveillance empire. The seventh floor was, in fact, only one part of a network of facilities. The most important outstation was the headquarters of the Post Office Special Investigations Unit near St. Paul's. MI5 had a suite of rooms on the first floor run by Major Denman, an old-fashioned military buffer with a fine sense of humor. Denman handled the physical interception of mail and installation of telephone taps on the authority of Post Office warrants. He also housed and ran the laboratory for MI5 technical research into ways of detecting and sending secret writing. Each major sorting office and exchange in the country had a Special Investigations Unit Room, under the control of Denman, to place taps and intercept mail. Later we moved the laboratories up to the Post Office Laboratory at Martlesham, Suffolk. Then, if a letter which had been opened in St. Paul's needed further attention, it was sent by motorcycle courier up to Suffolk.