The station is a huge open-ended hangar-like building with overhead gantries patrolled by guards brandishing machine guns. The S-Bahn's rolling stock, like the stations and the track, are ancient and dilapidated. The train came rattling in, its windows dirty and the lights dim. I got in. It was almost empty: those privileged few permitted to cross the border are not to be found travelling westwards at this time of evening. It took only a few minutes to clatter over the Wall. The 'anti-fascist protection barrier' is particularly deep and formidable here where the railway crosses the Alexander Ufer: perhaps the sight of it is intended to be a deterrent.

There is an almost audible sigh of relief from the passengers who alight at Zoo Station. I had to change trains for Grunewald, but there was only a minute or two to wait and it was quicker than taking a cab and getting tangled up in the Ku-Damm traffic which would be thick at this time.

From the station I walked to Frank Harrington's home. I approached it carefully in case there was anyone waiting for me. It seemed unlikely. The standard procedure was to cover the frontier crossing points-those for German nationals as well as the ones for foreigners – and the airport. On a Friday night at short notice that would provide more than enough problems. Frank as the Berlin chief was already given special protection by the civil police. My guess was that whoever was allotting the personnel would decide that Frank couldn't be afforded a car and a three-shift watch. They would describe me as a fugitive special category three: 'possibly armed but not dangerous'.

It was Axel Mauser – one of the kids at school here – who first showed me the proper way to climb drainpipes. Until then I'd been using my hands and getting my clothes into a terrible state. It was Axel who said, 'Climb ropes with your hands; drainpipes with your feet' and showed me how the burglars did it without getting their hands dirty. I don't know who showed Axel how to do it: his father probably. His father, Rolf Mauser, used to work in the hotel for Lisl. Rolf Mauser was an unscrupulous old crook. I'd believe almost anything of Rolf.

I was remembering all that as I climbed into the upstairs master bedroom of Frank's big house in Grunewald. There were no burglar alarms at the back. I knew where all the burglar alarms were. I'd helped Frank decide where to put them. And Frank always kept the bathroom window ajar. Frank was a fresh-air fiend. He'd often told me it was unhealthy to close the bedroom windows no matter how cold it was. Sometimes I think that's why his wife doesn't like living with him; she can't stand those freezing cold bedrooms. I told Fiona that once: she said don't be ridiculous but it didn't seem ridiculous to me. I can't stand cold bedrooms: I prefer unhealthy warmth.

Frank wasn't in bed of course, I knew he wouldn't be. That's why I got in upstairs. I got through the window and then had to stand there, carefully removing from the sill about three hundred bottles, tubes and sprays of bath oil, shaving soap, hair shampoo, toothpaste and God knows what. What could Frank ever want with all that stuff? Or was it the unredeemed property of Frank's girl-friends?

Finally I made a foot space on the window sill and from there I could step down into the bath and…Jesus, there was water in the bath. Lots of water! What did that bloody Tarrant do if he couldn't even make sure the bath was drained properly? My shoe was full of soapy water. How disgusting! I didn't like Frank's valet and the feeling was mutual. I suppose, if I was to examine my feelings closely, the principal reason I didn't just knock on Frank's front door was because I wouldn't trust that bloody man Tarrant as far as I could throw him. In a jam like the one I was now in, I would give Tarrant just three minutes before catching sight of me and getting on the blower and reporting me. Less than three minutes: thirty seconds.

Frank was downstairs. I knew where he was. I'd known it even when I was on the back lawn looking up at the drainpipes. He was sitting in the drawing room playing his Duke Ellington records. That's what Frank usually did when he was alone in the house. Volume up really loud, so that you could hear the drums and brass section halfway along the street. Frank said the only way you could really appreciate these old records was to have them as loud as the original band had been when making them, but I think Frank was going deaf.

It was the 1940 band – the best Ellington band ever in my opinion, although Frank didn't agree – playing 'Cotton Tail'. No wonder Frank didn't hear me come into the room. I could have been driving a combine harvester and still he wouldn't have heard me above the surging beat of the Ellington band.

Frank was sitting in a chair positioned exactly in line with his two giant speakers. He was dressed in a yellow sweater with a Paisley-patterned silk scarf tucked into his open-neck shirt. It was all very Noel Coward except for the big curly pipe in his fist and the clouds of fierce-smelling tobacco smoke that made me want to cough. He was bent low reading the small print on a record label. I waited for him to look up. I said, 'Hello, Frank,' as casually as I could say it.

'Hello, Bernard,' said Frank and held his pipe aloft to caution me. 'Listen to Ben Webster.'

Listen to him. How could I do anything else, the tenor sax solo went through my head like a power drill. But when the immortal Webster had finished, Frank turned the volume down so it was merely very loud.

'Whisky, Bernard?' said Frank. He was already pouring it.

'Thanks,' I said gratefully.

'I enjoy seeing you any time, Bernard. But I wish you'd just knock on the front door, the way other visitors do.'

If Frank knew there was a warrant out for me, he was staying very cool. 'Why?' I said and drank some whisky. Laphroaig: he knew I liked it.

'So you don't make such a mess on the carpet,' said Frank with a fleeting grin to offset his complaint.

I looked at the carpet. My wet shoe had left marks all the way to the door, and right through the house probably. I'm sorry, Frank.'

'Why do you have to do everything arse upwards Bernard? It makes life so difficult for your friends.' Frank had always taken his paternal role seriously, and his way of demonstrating it was to be there when I needed him. Sometimes I wondered what kind of man my father must have been to have made a friendship so deep and binding that I was still drawing upon its capital. 'You're too old now for tricks like climbing up to that damned bathroom. You used to do that when you were very young. Remember?'

'Did I?'

'I left the light on in the bathroom so you wouldn't fall off the ledge and break your neck.'

'You heard what happened?' I said, not being able to endure another moment of Frank's small-talk.

'I knew you'd come to me,' Frank said, walking towards me with a whisky bottle. He couldn't resist it. It was the sort of complacent statement my mother made. Why did he have to be such an old woman? Couldn't he see how it spoiled everything? I let him pour me another drink. It was a wonder he was able to resist telling me I drank too much, but he'd probably find some way to work it into the conversation before long.

'When did you hear?' I asked.

'That the old man wanted you collared? I got a "confidential" on the printer about four o'clock. But then a cancellation came through.' He smiled. 'Reading between the lines, someone in London must have decided that the old man had gone completely batty. Then, after an hour or more, the same message was repeated. This time with the names of both the D-G and the Deputy on it.' He looked at the carpet. 'It's not grease is it?'

'It's water,' I said.

'If it's grease or oil, tell me now so I can leave a note for Tarrant to do something about it before it soaks in.'