'No,' I said. I didn't want to get into a discussion about what I did for a living.

'Right from the time I was a child,' he continued. Tm going back a long time now to the war and even before that. There was a traffic cop, famous all over Berlin. Siegfried they called him; I don't know if that was his real name but everyone knew Siegfried. He was always on duty at the Wilhelmplatz, the beautiful little white palace where Dr Goebbels ran his Propaganda Ministry. There were always crowds of tourists there, watching the well-known faces that went in and out, and if there was any kind of crisis, big crowds would form there to try and guess what was going on. My father always pointed out Siegfried, a tall policeman in a long white coat. And I wanted a big white coat like the traffic police wear. And I wanted to have the ministers and the generals, the journalists and the film stars, say hello to me in that friendly way they always greeted him. There was a kiosk there on the Wilhelmplatz which sold souvenirs and they had postcard photos of all the Nazi bigwigs and I asked my father why there wasn't a photo card of Siegfried on sale there. I wanted to buy one. My father said that maybe next week there would be one of Siegfried, and every week I looked but there wasn't one. I decided that when I grew up I'd be the policeman in the Wilhelmplatz and I'd make sure they had my photo on sale in the kiosk. It's silly, isn't it, how such unimportant things change a man's life?'

'Yes,' I said.

'I know you from somewhere,' he said, looking at my face and frowning. I passed the police inspector my hip flask of brandy. He hesitated and took a look round the desolate yard. 'Doctor's orders,' I joked. He smiled, took a gulp, and wiped his mouth on the back of his hand.

'My God, it's cold,' he said as if to explain his lapse from grace.

'It's cold and it's Christmas Eve,' I said.

'Now I remember,' he said suddenly. 'You were in that football team that played on the rubble behind the Stadium. I used to take my kid brother along. He was ten or eleven; you must have been about the same age.' He chuckled at the recollection and with the satisfaction of remembering where he'd seen me before. 'The football team; yes. It was run by that crazy English colonel – the tall one with glasses. He had no idea about how to play football; he couldn't even kick the ball straight, but he ran round the pitch waving a walking stick and yelling his head off. Remember?'

'I remember,' I said.

'Those were the days. I can see him now, waving that stick in the air and yelling. What a crazy old man he was. After the match he'd give each boy a bar of chocolate and an apple. Most of the kids only went to get the chocolate and apple.'

'You're right,' I said.

'I knew I'd seen you somewhere before.' He stood looking across the water for a long time and then said, 'Who was in the ambulance? One of your people?' He knew I was from London and guessed the rest of it. In Berlin you didn't have to be psychic to guess the rest of it.

'A prisoner,' I said.

It was already getting dark. Daylight doesn't last long on clouded Berlin days like this in December. The warehouse lights made little puff balls in the mist. Around here there were only cranes, sheds, storage tanks, crates stacked as high as tenements, and rusty railway tracks. Facing us far across the water were more of the same. There was no movement except the sluggish current. The great city around us was almost silent and only the generator disturbed the peace. Looking south along the river I could see the island of Eiswerder. Beyond that, swallowed by the mist, was Spandau – world-famous now, not only for its machine guns but for the fortress prison inside which the soldiers of four nations guarded one aged and infirm prisoner: Hitler's deputy.

The police inspector followed my gaze. 'Not Hess,' he joked. 'Don't say the poor old fellow finally escaped?'

I smiled dutifully. 'Bad luck getting Christmas duty,' I said. 'Are you married?'

'I'm married. I live just round the corner from here. My parents lived in the same house. Do you know I've never been out of Berlin in all my life?'

'All through the war too?'

'Yes, all through the war I was living here. I was thinking of that just now when you gave me the drink.' He turned up the collar of his uniform greatcoat. 'You get old and suddenly you find yourself remembering things that you haven't recalled in about forty years. Tonight for instance, suddenly I'm remembering a time just before Christmas in 1944 when I was on duty very near here: the gasworks.'

'You were in the Army?' He didn't look old enough.

'No. Hitler Youth. I was fourteen and I'd only just got my uniform. They said I wasn't strong enough to join a gun crew, so they made me a messenger for the air defence post. I was the youngest kid there. They only let me do that job because Berlin hadn't had an air raid for months and it seemed so safe. There were rumours that Stalin had told the Western powers that Berlin mustn't be bombed so that the Red Army could capture it intact.' He gave a sardonic little smile. 'But the rumours were proved wrong, and on December fifth the Americans came over in daylight. People said they were trying to hit the Siemens factory, but I don't know. Siemensstadt was badly bombed, but bombs hit Spandau, and Pankow and Oranienburg and Weissensee. Our fighters attacked the Amis as they came in to bomb – it was a thick overcast but I could hear the machine guns – and I think they just dropped everything as soon as they could and headed home.'

'Why do you remember that particular air raid?'

'I was outside and I was blown off my bicycle by the bomb that dropped in Streitstrasse just along the back of here. The officer at the air-raid post found another bike for me and gave me a swig of schnapps from his flask, like you did just now. I felt very grown up. I'd never tasted schnapps before. Then he sent me off on my bike with a message for our headquarters at Spandau station. Our phones had been knocked out. Be careful, he said, and if another lot of bombers come, you take shelter. When I got back from delivering the message there was nothing left of them. The air defence post was just rubble. They were all dead. It was a delayed action bomb. It must have been right alongside us when he gave me the schnapps, but no one felt the shock of it because of all the racket.'

Suddenly his manner changed, as if he was embarrassed at having told me his war experiences. Perhaps he'd been chafed about his yarns by men who'd come back from the Eastern Front with stories that made his air-raid experiences seem no more than minor troubles.

He tugged at his greatcoat like a man about to go on parade. And then, looking down into the water at the submerged car again, he said, 'If the next go doesn't move it, we'll have to get a big crane. And that will mean waiting until after the holiday; the union man will make sure of that.'

'I'll hang on,' I said. I knew he was trying to provide me with an excuse to leave.

'The frogmen say the car is empty.'

'They wanted to go home,' I said flippantly.

The inspector was offended. 'Oh, no. They are good boys. They wouldn't tell me wrong just to avoid another dive.' He was right, of course. In Germany there was still a work ethic.

I said, 'They can't see much, with the car covered in all that oil and muck. I know what it's like in this sort of water; the underwater lamps just reflect in the car's window glass.'

'Here's your friend,' said the inspector. He strolled off towards the other end of the wharf to give us a chance to talk in private.

It was Werner Volkmann. He had his hat dumped on top of his head and was wearing his long heavy coat with the astrakhan collar. I called it his impresario's coat, but today the laugh was on me, freezing to death in my damp trench coat. 'What's happening?' he said.