'They had no warning, Werner. I made sure Bret didn't know what I was going to do. And until the last minute when you came to London and told Dicky, no one at London Central knew I was going to pull Brahms Four out.'

'Your wife knew; she ran. She could have told Bret.'

'Not enough time,' I said. 'I thought of that, but there wasn't enough time for Bret to find out and get a message to Moscow.'

'So Bret is suspect and the D-G has put him on ice while he decides what to do about it?'

'It looks that way,' I said.

'Only the Miller woman knows the truth, I suppose,' said Werner. There was some unusual expression in his face that made me look at him closely.

'And she's in the Havel,' I said.

'Suppose I told you that I'd seen the Miller woman?'

'In the morgue? Did she come out at Spandau locks?'

'She's not dead,' said Werner smugly. 'I saw her looking fit and well. She's a clerk. She works in the Rote Rathaus.'

The Red Town Hall was the municipal centre for East Berlin, a massive red-brick building near Alexanderplatz, which, unlike so much around it, had survived for well over a century. 'Alive and well? You're sure?'

'Yes, I'm sure.'

'What's it all about then? Who is she? Was it all a stunt?'

'I found out a little about her – I have a friend who works there. Everything she said about her father living in England and about being married and so on seems to be true. I couldn't actually check her out, of course, but the story she gave you was true, as far as her identity is concerned.'

'She just forgot to mention that she was a resident of the Democratic Republic and worked for the government.'

'Right,' said Werner.

'What luck that you spotted her! I suppose they thought she was tucked well away from us in that place. There wasn't much likelihood of anyone who'd seen her on this side going into an office in the East Berlin town hall.'

'It was a million to one chance that I had to go there again. I remembered her because she once helped me with a tricky problem. An East German truck I use broke down in the West on a delivery trip. I went round in circles trying to find someone who had the necessary permissions to tow it from West to East. That was a year or more ago. Then, last week, I was in there again getting my ration cards.'

'And she didn't recognize you? She must have seen you that night they arrested her and I got her to give me a statement.'

'You did the interrogation. I waited outside. I only caught sight of her very briefly. I knew I'd seen her somewhere before, but I couldn't think where. I mean, it's not the sort of face you never forget. Then, after I'd given up and stopped thinking about her, I walked into the Rathaus and saw her sitting at her desk. This time I took a close look at her.'

'She was no amateur, Werner. She made her suicide attempt convincing enough to get herself slammed into the Steglitz Clinic.'

'Suicides in police cells – cops get very nervous about such things, Bernie. I looked into it. He was a young cop on duty at night. He played it safe and sent for an ambulance.'

'And then they covered their tracks by taking her from the Steglitz Clinic and running the ambulance into the water.'

'It must have been a diversion while another car took her across to the East.'

'It worked all right,' I said. 'When I remember spending my Christmas Eve standing on that freezing cold wharf, waiting for them to lift that bloody vehicle…'

'I hope you're not going to suggest trying to get hold of her again. We couldn't grab her, Bernie, not there in the Mitte. They'd have us in the bag before we even got her to the car.'

'It would be difficult, wouldn't it?'

'It wouldn't be difficult,' said Werner. 'It would be impossible. Don't even think about it.'

'You'd better put all this in writing, Werner.'

'I've got it drafted out. I thought I'd wait until I came to London so I could check with you first.'

'I appreciate that, Werner. Thanks.'

We sat for a few minutes drinking the coffee and not saying anything. I was fully occupied in trying out all the configurations that this new piece of the jigsaw puzzle presented.

Then Werner said, 'How does this affect Bret?'

'You didn't tell the committee anything about this Miller woman being alive, did you?'

'You said not to tell them departmental secrets. This seemed like a departmental secret.'

'So secret that only you and I know of it,' I said.

'That's right,' said Werner.

'Why, Werner? What the hell was it all about? Why did they use the Miller woman to pick up the material?'

'Suppose everything she told you was exactly true. Suppose she had been a radio operator handling the material from Bret Rensselaer and the stuff from your wife. Suppose Fiona pulled her out when she went over to them. The Miller woman decides she's getting too old for espionage and tells Moscow that she wants to get out cf the business – she wants to retire. Fiona encourages her because the Miller woman knows too much. So they find her an easy little job issuing licences in the town hall. It happens all the time, Bernie. Probably she has a small pension and card for the Valuta shops so that she can buy Western goods. Every thing is lovely, everyone is happy. Then one day, at short notice, they need someone to go to Wannsee and pick up the package. They need someone who has the right sort of papers for coming over to the West side of the city. It seems like a routine task. Little likelihood of danger. She'll only be in the West for a couple of hours, and she won't be searched by anyone on the West side when she goes through with the package.' He fiddled with his coffee spoon, pushing it backwards and forwards. 'Or perhaps it's not a one-off. Perhaps she does a lot of little jobs like that to eke out her salary. Either way, I have no trouble believing it. There's nothing that doesn't fit together.'

'Maybe not. But that's not the way I'd treat someone like her. Imagine that we had been running a truly remarkable source in the KGB offices in Moscow. Would we let a case officer or radio operator for that agent go back over there for ten minutes, let alone a couple of hours? You know we wouldn't.'

'The KGB are different,' said Werner. He drove the spoon around the table, cornering recklessly when it came to the fruit bowl.

'Maybe they are, but my supposition isn't complete yet. What if they not only had one remarkable source but two remarkable sources? And one of them is still in place, Werner – a source right in London Central still going strong. Are the KGB so different that they'd still let the Miller woman go and put her head in a noose? Would they take a chance on her being arrested and telling us enough to blow their other agent?'

'It's no good trying to think the way they think. That's the first thing I had to learn when I started dealing with them. They don't think like us. And you're being wise after the event. They had no idea that we were going to move in on that party at Wannsee. To them it must have seemed like the most routine and safe assignment possible.' Werner tried to drink from the cup he'd already emptied. Even when he knew it was empty, he tipped his head right back to get the final drips. He hadn't touched his brandy.

'I still find it difficult to believe they'd take the risk,' I said.

'What risk? Our people risk everything when they go through the Wall. They risk the detailed inspection of documents, the guards watching every move they make and listening to everything they say. There are the secret marks made on the passports and travelling papers. Everyone going East is scrutinized under a microscope no matter who they are. But what do their people risk when they come to spy on the West? No one crossing to our side is inspected very closely. Being a KGB agent is one of the safest jobs going. We're a walkover, Bernie. That woman's job was a sinecure. It was a million-to-one chance that she was swept up by the arrest team.'