One theory out of hundreds is that he never went up to the apartment at all, and that they took him straight through the building and out the other side, and that the figure in the window was one of their own people, for instance one of the tall men in the photograph taken in the VAAP foyer that afternoon. It never seemed to me to matter, but to the experts for some reason it did. When a problem threatens to engulf you, there's nothing like irrelevant detail to keep your head above water.

Speculation about Barley's disappearance began slowly and built throughout the night. Optimists like Bob, and for a while Sheriton, clung on till dawn and after. Barley and Bluebird had drunk themselves under the table again, they kept insisting in order to keep each other's spirits up. It was Peredelkino all over again, a re-run, no question, they told each other.

Then for a short while they worked up a kidnap theory, until soon after five-thirty in the morning - thanks to the time difference - when Henziger and Wicklow had their letters and Wicklow without further fuss took a cab to the British Embassy, where the Soviet guards at the gate did not obstruct him. The result was a flash signal to Ned, decypher yourself, from Paddy. Meanwhile, Cy was putting through a similar message to Langley, Sheriton and anyone else who was still willing to listen to a man whose Moscow days looked like being over very soon.

Sheriton took the news with his customary phlegm. He read Cy's telegram, he looked around the room and realised that the whole team was watching him – the smart girls. the boys in ties, loyal Bob, ambitious Johnny with his gunman's eyes. And of the Brits, Ned, myself and Brock, for Clive had prudently discovered urgent business elsewhere. There was a lot of the actor in Sheriton, just as there was in Henziger, and he used it now. He stood up, he hauled at his waistband, he massaged his face like a man reckoning he needed a shave.

'Well, boys. Better put the chairs on the tables till next time.'

Then he walked over to Ned, who was still sitting at his desk studying Paddy's telegram, and he laid a hand on Ned's shoulder.

'Ned, I owe you dinner some time,' he said.

Then he walked over to the door and unhooked his new Burberry and buttoned himself into it and departed, followed after a moment by Bob and Johnny.

Others did not bow out so elegantly, least of all the barons of the twelfth floor.

Once again, a committee of enquiry was formed.

Names should be named. Nobody should be spared. Heads must roll.

The Deputy to chair it, Palfrey to be secretary.

Another purpose of such committees, I discovered, is to impart a sense of ceremony to events that have passed off without any. We were extremely solemn.

The first to be heard, as usual, were the conspiracy theorists, who were recruited in short order from the Foreign Office, the Defence Ministry and a rather unlovely body called the Informal Consultants, which consisted of industrial and academic scientists who fancied themselves as Sunday spies. These amateur espiocrats commanded huge influence around the Whitehall bazaars, and were heard at inordinate length by the committee. A professor from Edinburgh addressed us for five full pipe-loads and nearly gassed us all, but nobody had the nerve to tell him to put the damn thing out.

The first great question was, what would happen next? Would there be expulsions, a scandal? What would become of our Moscow station? Had any of the irregulars been compromised?

The audio truck, though Soviet' property, was an American problem, and its abrupt disappearance caused hushed concern among those who had favoured its use.

The question of who is expelled for what is never a plain one, for heads of station in Moscow, Washington and London are these days declared to their host countries. Nobody in Moscow Centre had any illusions about Paddy's activities, or Cy's. Their cover was not designed to protect them from the opposition, but from the gaze of the real world.

In any case, they were not expelled. Nobody was expelled. Nobody was arrested. The irregulars, who were stood down indefinitely, went peaceably about their cover jobs.

The absence of a retaliatory gesture was quickly seen by Western pundits as vastly significant.

A conciliatory move in the season of glasnost ?

A clear signal to us that the Bluebird was a gambit to obtain the American shopping list?

Or a less clear signal to us that the Bluebird material was accurate, but too embarrassing to acknowledge?

The battle-lines were set. Somewhat along the principle that Ned had already explained to me, doves and hawks on both sides of the Atlantic once more gleefully parted company.

If the Sovs are sending us a signal that the material is accurate, why then clearly the material is inaccurate, said the hawks.

And vice versa, said the doves.

And vice versa again, said the hawks.

Papers written, feuds waged. Promotions, sackings, pensions, medals, lateral postings and downgradings. But no consensus. just the usual triumph of the fattest, disguised as rational deduction.

In our committee Ned alone refused to join the dance. He seemed cheerfully determined to accept the blame. 'The Bluebird was straight and Barley was straight,' he repeated to the committee over and again, without once losing his good humour. 'There was no deception by anyone, except where we deceived ourselves. It was we who were crooked. Not the Bluebird.'

Soon after he had delivered himself of this judgment, it was agreed he was under mental stress and his attendance was required more sparingly.

Oh, and note was taken. Passively, since active verbs have an unpleasant way of betraying the actor. Very serious note. Taken all over the place.

Note was taken that Ned had failed to advise the twelfth floor of Barley's drunken breakout after his return from Leningrad.

Note was taken that Ned had requisitioned all manner of resources on that same night, for which he had never accounted, among them Ben Lugg and the services of the head listener Mary, who sufficiently overcame her loyalty to a brother officer to give the committee a lurid account of Ned's high-handedness. Demanding illegal taps! Imagine! Faulting telephones! The liberty!

Mary was pensioned off soon after this and now lives in a rage in Malta, where it is feared she is writing her memoirs.

Note was also taken, if regretfully, of the questionable conduct of our Legal Adviser dePalfrey – I even got my de back – who had failed to justify his use of the Home Secretary's delegated authority in the full knowledge that this was required of him by the secretly agreed Procedures Governing the Service's Activities as Amended by etcetera, and in accordance with paragraph something of a deniabIc Home Office protocol.

The heat of battle was however taken into account. The Legal Adviser was not pensioned off, neither did he take himself to Malta. But he was not exonerated either. A partial pardon at best. A Legal Adviser should not have been so close to an operation. An inappropriate use of the Legal Adviser's skills. The word injudicious was passed around.

It was also noted with regret that the same Legal Adviser had drafted a glowing testimonial of Barley for Clive's signature not forty-eight hours before Barley's disappearance, thus enabling Barley to take possession of the shopping list, though presumably not for long.

In my spare hours, I drew up Ned's terms of severance and thought nervously about my own. Life inside the Service might have its limitations but the thought of life outside it terrified me.

The announcement of Bluebird's passing provided a temporary setback to our committee's deliberations. but it soon recovered. The offending item was a sixline affair in Pravda , carefully pitched to be neither too much nor too little, reporting the death after illness of the distinguished physicist Professor' Yakov Savelyev of Leningrad and listing his several decorations. He had died of natural causes - the bulletin assured us - soon after delivering an important lecture to the military academy at Saratov.

Ned took the day off when this news reached him, and the day became three days, a light flu. But the conspiracy theorists had a ball.

Savelyev was not dead.

He had been dead all along, and the version we had dealt with was an impostor.

He was doing what he had always been doing, running the Scientific Disinformation Section of the KGB.

His material was vindicated, was not vindicated.

It was worthless.

It was pure gold.

It was smoke.

It was a truthful message of peace sent to us at immense risk by the moderates inside Moscow's ruling ranks in order to show us that the Soviet nuclear sword had rusted in its scabbard and the Soviet nuclear shield had more holes in it than a colander.

It was a fiendish plot to persuade the American fainthearts to take their fingers off the nuclear trigger.

In short, there was enough for everyone to get their teeth into.

And, because in the symbiotic relationship that exists between belligerent states nothing can take place in the one without setting off a mirror reaction in the other, a counterindustry grew up and the history of the American part in the Bluebird affair was hastily rewritten.

Langley knew all along that the Bluebird was bad, said the counter-industry.

Or that Barley was.

Or that both of them were.

Sheriton and Brady were playing double-double games, said the counter-industry. Their one aim was to plant the smoke convincingly and steal another march on the Russians in the endless struggle for the Margin of Safety.

Sheriton was a genius.

Brady was a genius.

They were all, all geniuses!

Sheriton had scored a brilliant coup. Brady had.

The Agency was staffed by nothing but brilliant strategists who were quite unlike their dismal counterparts in the overt world. God preserve the Agency. Where would we be without it?

As if all this were not enough, new tiers of possibility were added to the old. For example, that Sheriton had been the unwitting instrument of the Pentagon and Defense. It was they who had prepared the phoney shopping list and they who had known all along that the Bluebird was a plant.

And each fresh rumour had to be taken seriously in its turn, even if the only real mystery was who had fabricated it or why. The answer, in many cases, appeared to be Russell Shcriton, who was fighting for his hide.

As to the Bluebird, if he had not died of natural causes. he was certainly doing so now.