'You're not going nuts,' I said.

'Did you tell me your name?'

'No, I didn't.'

'I'm not going nuts,' said Johnson. 'It's these Austrians who are going nuts. Give me a double scotch,' he called to the barman. He raised his eyes and I nodded. 'Make it two double scotches.'

'Let me pay,' I said. 'I suddenly seem to have a lot of cash.'

'Me too,' he said and laughed. 'I've got to get out of here, these people drive me crazy. Want a ride to the airplane? Or have you got a car?'

'When?'

I'm catching the seven o'clock plane to Vienna,' he said, and I told him that would suit me just fine. The whisky calmed him down. I let him talk about his stamps while I made appropriate interjections and thought about other things.

Later I walked upstairs with him. His room was near the stairs and mine along the same corridor. As he let himself into his room he said, 'I'll take a bath and maybe grab a sandwich. See you in the lobby about five-thirty?'

'Right,' I said.

Then, as his door closed I heard him say, 'Well, what about that?' and I wondered what he was referring to. But by that time I'd grown used to his spirited disposition and decided that he was talking to himself.

There was plenty of time. I wondered whether to phone London and tell them that someone else had bought the cover but decided to put it off for an hour or two. By that time I'd be speaking to a Duty Officer rather than to Dicky or Stowe.

I went to the window and stared down at the rainswept street. The tourists were indomitable. Buttoned tight in long brightly coloured plastic coats, their feet encased in transparent overshoes, their hoods with drawstrings tightened to reveal small circles of grim red faces, they trekked past like combat-hardened veterans resolutely moving up to the fighting line. I got a glass from the bathroom and poured myself a shot of duty-free scotch. I'd promised Gloria not to touch the hard stuff while I was away this time, but that was not taking into account the fiasco in the auction room and the way in which I would soon have to explain my failure.

I kicked my shoes off, stretched out on the bed and dozed. All day – like an errant poodle tugging its leash – my mind had tried to explore some other time and place. And yet these fugitive memories remained fuzzy grey and unfocused. It was when I closed my eyes and relaxed that my memories sniffed out what had been bothering me all day.

'Deuce' Thurkettle! Jesus Christ, how could I ever have forgotten Deuce Thurkettle, even if he now preferred to be known as Ronnie? I'd never known him but his dossier was something not to be forgotten.

'Deuce' not in the sense of runner-up, quitter or coward, the way the word is sometimes used, nor a 'pair' in a poker game. This man was Deuce because of the barbaric double murder for which he'd gone to prison. Deuce Thurkettle came to Berlin after being released from some high-security prison in Arizona, where he was serving a life sentence for murder in the first degree.

Perhaps it was a long dull afternoon after too much Southern-fried chicken when some bright young fellow sitting behind a desk in Langley, Virginia, had got this brilliant idea of sending a convicted murderer into Berlin on a tourist visa, to get rid of a troublesome KGB agent who had so far eluded all attempts to incriminate him.

I remembered the Deuce Thurkettle file and the way I'd read it all the way through without pause. I suppose to some extent I read it because I was not supposed to see it. It was a CIA document buried deep in the dank dark place where the CIA buried their secrets. Or that's where it should have been. Poor old Peter Underlet had taken it home with him. He had shown it to me one evening after the two of us had dinner – and two bottles of lovely Château Beychevelle 1957 – in his apartment. I could recollect each page of that bizarre insight into the cloistered mentality of the administrator: '… and Thurkettle's knowledge of electronic timing devices, sophisticated locks, modern handguns and explosives, added to his proved physical resources, qualify him as an outstanding field agent.'

Underlet had opened the file to that page of a long report from Langley before he slammed the whole thing on to my knees. 'Look at that,' said Underlet bitterly. 'That's what those shits in Washington think about field agents. Without any training or experience this murdering bastard becomes a field agent overnight, an outstanding field agent it says there.'

I remember Underlet slumping back in the armchair and drinking his wine and saying nothing while I read the file through. 'Deuce'

Thurkettle; how could I have forgotten him, the first of a trio of hit men who came unbidden and unwelcome to the CIA offices of Europe during that unhappy period?

Afterwards – weeks afterwards – we talked about it again. By that time I had become more indignant about the morality of Washington DC than about what the episode revealed of the desk-man's feelings about field agents.

I was no longer stretched out, I was sitting up in bed fully aware of the racing pulse and tension that comes when the mind is on the verge of remembering some important image. What happened to those three jailbirds? All three were given the elaborate new identities that later became the reward for mafiosi who turned State's evidence. Thurkettle: Thurkettle. There was speculation that he murdered a supermarket tycoon in Cologne: a man with whose wife Thurkettle had a love affair. I wasn't sure that was Thurkettle. Had Thurkettle's name been in any of those 'most wanted – confidential' lists? My memory just could not get hold of it.

By now I was on my feet. I paced the room knowing beyond any doubt that it all added up to a conclusion that would seem obvious when the questions were asked. Obvious, that is to say, to the questioner.

I decided to ask Johnson some more questions: about Thurkettle and anything else that emerged. I put on my shoes and went down the corridor to knock at the door of Johnson's room. There was no response. I turned the knob and found the door unlocked.

Inside, the bedroom was empty. A clean shirt, underclothes and socks were laid out on the bed, in the careful way a valet might arrange clothes for a fastidious employer. From the bathroom there came the sound of water running. The door was closed. Johnson called, 'Put it down on the table. There's a tip there for you.'

'It's not room service: it's me,' I said.

'You're early aren't you?' His voice was distorted like that of a man cleaning his teeth.

'That guy Thurkettle. I remembered something about him.'

'Give me fifteen minutes.' There was a splutter as if the tooth cleaning was proceeding energetically.

Okay, I thought, everything is normal. I went back to my room. I don't know how long I sat there before the sound of the explosion made me jump out of the chair and run for the door. Afterwards the newspapers said the forensic department estimated it at 300 grams of explosive, but that amount would have taken the bathroom door off and maybe the wall and me too.

But it was a loud bang all the same, and that unmistakable stink of explosive came rolling down the corridor to meet me. My mind went blank. Experience said hide under the bed: curiosity made me wonder what had happened.

For better or worse, I hurried along the corridor and into Johnson's room. I went to the bathroom and grabbed the handle as the door fell off its hinges. I don't know what kind of explosive they'd used but the inside of the bathroom was black with soot and dirt. Maybe that had come from something else. The wash-basin was the centre of the damage: the mirror had disappeared, except for a couple of splinters dangling from the fixing screws. Below it, looking like some example of modern sculpture, the blue china pedestal remained in position supporting one elegant slice of basin.