I carried my first 9-mm. automatic Browning when I was just twenty years old. I was a National Service second lieutenant in the Intelligence Corps in Austria. It was my first clandestine mission, and I was in heaven. The year, I think, was 1952, and I was stationed in Graz, the hub of the British Occupied Zone in the early Cold War years. The gun was loaded. On the advice of the Air Intelligence Officer, or A.I.O., in charge of the operation, I wore it jammed into my waistband against my left hip with the butt foremost, allowing for an easy draw across the body. Over it I wore a green loden coat, borrowed under a pretext from one of our Field Security drivers, and, for additional cover, a fetching green Tyrolean hat, bought at personal expense. Such was my disguise of choice for a top-secret night trip through sparsely populated countryside to Austria’s border with Communist Czechoslovakia.

The author in Hamburg, in the early nineteen-sixties. Photograph by Ralph Crane / Time Life Pictures / Getty Images

The A.I.O., however, had opted for the more traditional spy’s attire: fawn raincoat and trilby hat, which, together with his military mustache, gave him, to my callow eye, a rather too British look. But he knew best. The A.I.O. was a veteran of the business, as we National Service fledglings had often been reminded sotto voce by our seasoned superiors in the bar of the Wiesler hotel, reserved for British officers, where the A.I.O. could be observed of an early evening, always seated in the same corner and half-hidden by his Austrian newspaper, with a mahogany whiskey at his side and a crisp white handkerchief jammed into the cuff of his officer-class sports jacket. The A.I.O., they said, had done his share of this and that—as ever with the clear implication that we hadn’t.

As became a man of mystery, the A.I.O. was a solitary. His office, which we never entered, was situated in the attic of the elegant villa on the edge of town that our military masters in Vienna had requisitioned for us Intelligence types. Spy ethic dictates that the higher up the building you go the more secret it gets, which explains why we mere Field Security trash were confined to the ground floor. But I knew his window. It was a dormer, thick with grimy net curtains. He had no known rank, and no known staff. He made no use of our mailroom. We assumed, but were never told, that he relied on his own communications system. Just occasionally, a standard tin box of papers would arrive for him by way of the Army Field Post Office, and although it looked exactly like the sort of junk we ourselves were handling, he would immediately hasten downstairs and, with an air of immense gravity, return with it to his aerie. He was said to be much decorated, but we never saw him in uniform. In short, he was the real McCoy. His work might look as boring as ours, but in reality he was an undercover Friend, meaning a member of M.I.6, the highest form of Intelligence life known to man.

Why me, sir? I asked him, when he suggested we take a quiet stroll along the river.

“Because you’ve got what it takes,” he replied, in the bitten-off style of a man who would prefer not to be speaking at all.

How do you know I have, sir? I asked.

“Been watching you.”

Our car was an innocent black Volkswagen Beetle with civilian plates. The A.I.O. explained that he had got it from Intelligence Organization Vienna, which, as far as I was concerned, was the summit of Olympus. Should we by chance be stopped by the Austrian police, he said, we were two businessmen from Graz interested in buying farmland for cash. This would explain the ten thousand U.S. dollars in the brown briefcase lying on the back seat of the Beetle. The dollars also came from Int. Org. Only when all else failed, he said, should we flash our cards and declare ourselves to be British military personnel engaged on secret duties.

At first as we drove I could think only of the Browning nudging at my hip. But as the night darkened and my body eased and the Browning grew warmer, we became a pair, which was what the A.I.O. had said we would do. “Think of it as part of you,” he advised. So I did, even if from time to time I discreetly fingered the safety catch to make sure it was still on.

In what sort of situation might I be using it, sir? I asked.

“Contingency. If the Czech goons come after him, we give him covering fire. Not till I tell you, mind.” And, as an afterthought, “Don’t go for the legs. Aim for the mark.”

The mark?

“Shoulders to groin and all points between.”

My thoughts turned to the brave man we had come to meet: a high-ranking officer in the Czech Air Force, risking death and worse to bring precious information to the West. At this very moment, said the A.I.O., our man was creeping over the border with the aid of sympathetic frontier guards.

How about dogs? I asked.

“Drugged.”

Once across, said the A.I.O., who was a stickler for need-to-know, our man would proceed to a certain frontier village just inside Austria, and this was the village we were heading for. Its name remained secret right up to the moment when the signpost blew it.

Is he defecting, sir?

The A.I.O. looked grim and shook his head. “Man’s got a wife and kids, for God’s sake. It’s a one-time sell.”

And then he’ll go back?

“If he can.”

And if he can’t?

The A.I.O.’s silence was more eloquent than words.

A tiny inn stood at the empty roadside. Light burned yellow in the windows. The only sound was of male voices, which stopped dead as soon as we walked in. The A.I.O. went ahead in case there was trouble. I followed with the briefcase. In a single low-ceilinged room, a score of peasants in blue overalls stared at us in mute amazement through the tobacco smoke. A billiards table occupied the center of the room. Nobody was playing. A vacant bench stood next to the bar. The A.I.O. sat on it. With the briefcase at my feet, I sat beside him, observed by the peasants. The A.I.O. ordered two beers in snappish, swallowed-up German. Today I wonder whether “two beers” was the only German he knew. The landlord set them in front of us, and the echo as they hit the table seemed to go on forever.

“Fancy a game of billiards?” the A.I.O. muttered, in English, out of the corner of his mouth.

Love one, I muttered back.

The gun was indeed part of me: so much so that I had ceased to notice its presence on my hip. Stooping to address the ball, I was startled by the clang of a heavy metal object striking the tiled floor, and looked around to identify the source. Finally, I saw the Browning lying at my feet, but by then the inn had emptied itself of customers and landlord. I retrieved it, returned it to my waistband, and picked up the briefcase.

“Abort,” the A.I.O. ordered, pausing only to finish his beer.

His composure astonished me. Not a word of rebuke. We returned to the Volkswagen, sat in it, and waited. For whom? The Austrian police? Or our intrepid spy? The A.I.O. seemed at ease with either possibility, but neither appeared. He had a flask of Scotch and we took pulls from it. The dawn came, and somehow the purpose of our great mission evaporated. With a philosophical sigh, the A.I.O. started the engine and set course for Graz.

As with all great intelligence operations, ours had no known outcome—or none to me. Did the brave Czech airman ever make his attempt? I had no chance to ask. A couple of days later, the A.I.O. had vanished, leaving no forwarding address. Did he give back the ten thousand dollars, or keep the money for another day? In “A Perfect Spy,” I made some use of the story, but my larger purposes did not allow me to give it the status it deserved as an account of my hero’s first armed exploit On Her Majesty’s Secret Service.

Nevertheless, with the ripening of years, I think I have hit upon an answer to the questions that have troubled me for so long. There was no Czech officer crossing the border that night. The briefcase did not contain ten thousand dollars; at best, there was an old pair of pajamas and a reserve bottle of Scotch. The A.I.O. was not the favored son of Int. Org., he was not an undercover officer of M.I.6, his work was just as tedious and useless as ours. He was one of those forgotten souls whom military bureaucracies dump on distant shores and forget about for years on end.

He was, in addition—if discreetly—mad, and living in a secret bubble all his own, a condition that in the spook world, rather like a superbug in a hospital, is endemic, hard to detect, and harder still to eradicate.

I can also hazard a guess about the nature of his madness, since from time to time I have experienced similar symptoms. The A.I.O., like the rest of us, dreamed the Great Spy’s Dream. He imagined himself at the Spies’ Big Table, playing the world’s game. Gradually, the gap between the dream and the reality became too much for him to bear, and one day he decided to fill it. He needed a believer, so I got the job. I was well cast. Years later, for a short time, I did actually become an insider in the world that the A.I.O. pretended to inhabit, but it wasn’t long before I, too, was fantasizing about a real British secret service, somewhere else, that did everything right that we either did wrong or didn’t do at all.

My solution was to invent a spook world better suited to my needs, just as the A.I.O. had done. It was only our methods that were a little different.

My agreeable middle-aged roommate in the British Security Service, better known as M.I.5, was, I think, afflicted by a similar strain of the disease, although the symptoms in his case were different. But that is the nature of the disease.

I am speaking of the period of the Great Paranoia Epidemic that ran from the nineteen-fifties into the seventies, when practically everyone in M.I.5 above a certain rank, up to Sir Roger Hollis, the Director General, was suspected of being a Russian spy. The virus infected swaths of Whitehall and Westminster, but it was the spies who were worst hit, and they did it to themselves, on the strident insistence of America’s intelligence community.

The bacillus had begun its life in America, before sweeping eastward. First had come the Joe McCarthy era. McCarthy died in 1957, but his torch was quickly retrieved by a deranged C.I.A. inpatient of vast persuasive powers named James Jesus Angleton, who preached that the whole of the Western spook world was being controlled by superheads in the Kremlin. In human terms, Angleton’s apocalyptic vision was forgivable. He had received his education in the black arts of double cross at the knee of one Kim Philby, a long-standing double agent in the service of the Kremlin and, as head of the M.I.6 station in Washington, Angleton’s bosom buddy. If any spy ever needed an excuse for going off his head, it was James Jesus Angleton: fabled poker player, master of the spook universe, who woke up one morning to be told that his revered mentor, confessor, and fellow-boozer, Kim Philby, was a Russian spy.

But that doesn’t excuse the C.I.A., which made a folk hero of its mad doctor, and looked on while he poisoned the family. Not only did Angleton single-handedly immobilize his own agency. He then, with his masters’ blessing, performed the same service for its closest allies, to the ribald laughter of the K.G.B. Was Angleton ever invited to address the only logical conclusion to his thesis—namely, to close down the entire Western intelligence apparatus before the Russians led us over the cliff? I doubt it.

And M.I.5, assailed by the Angleton theory, rose superbly to the challenge. It was not content with spying on its own members; a cabal of middle and senior officers also found time to spy on Harold Wilson, the British Prime Minister, an episode in M.I.5 history that was documented in a dubious memoir put out by one of the conspirators. The author, you may remember, was Peter Wright, another poker pal of Angleton’s. Strenuous efforts by the British government to suppress the book assured it a wide readership.

The atmosphere in those days in the corridors of Leconfield House, on Curzon Street, was therefore very much as I portrayed it in “Tinker, Tailor, Soldier, Spy,” and it was the atmosphere that prevailed in the corridor that led to the little room that my colleague—I’ll call him Arthur—and I shared. In my memory, it is hushed, with furtive footsteps going past. It was my first in-house appointment.

Arthur was an M.I.5 paper-pusher of the old school: a meticulous, unadventurous, nine-to-six loyalist, with no ambitions to become what he was not. He had something of the donnish librarian about him, with bubbly gray hair overflowing at the sides, rimless spectacles, and an air of huge diligence and bustle. Sometimes he would humph, sometimes tut-tut, but he was always busy and never took a lunch hour: which was one good reason that the overworked internal-security staff decided that he was a Russian spy.