'It was good for me. I was top for mathematics two years running. My dad was amazed.' There was a crash of thunder and a blue flash of lightning.

'Even then, old Storch kept on at you.'

'He hated the English. His son was killed fighting in the Libyan Desert. He told the boys in the top class that the English had shot all their prisoners.'

'That was just propaganda,' said Werner.

'You don't have to spare my feelings,' I said. 'There are bastards everywhere, Werner. We both know that.'

'Storch didn't have to take it out on you.'

'I was the only Engländer he could get his hands on.'

'I've never heard you say a bad word about old Storch.'

'He was a tough-minded old bastard,' I said. 'He must have known that one word to my dad about him having been a stormtrooper would have got him kicked out of his job, but he didn't seem to care.'

'I would have squealed on him,' said Werner.

'You hated him more than I did.'

'Don't you remember all that poisonous stuff about Jewish profiteers, and the way he stared at me all the time?'

'And you said, "Don't look at me, sir, my father was a gravedigger." '

'That was when old Herr Grossmann was away on sick leave, and Storch did the history lessons.' A long roll of thunder sounded as the storm moved over the city and headed for Poland, such a short drive down the road. Werner scowled. 'All Storch knew about history was what he'd read in his Nazi propaganda – about how the Jewish profiteers had made Germany lose the war and ruined the economy. They should never have let a bigot like that take the history class.'

'I think I know what you're going to say, Werner.'

Werner sat down on the sagging armchair, smiled at me, and, although I knew what was coming, he said it anyway. 'One man was the very worst scoundrel, he told us. Already rich – he amassed a second fortune in a few months. He borrowed from the central bank to buy coal mines, private banks, paper mills and newspapers. And he paid back the loans in money so devalued by inflation that this whole spread cost him almost nothing.'

'It sounds like you've been looking at the encyclopedia, Werner,' I said. Hugo Stinnes. 'Yes, I was thinking of that long passionate lecture from old Storch only the other day.'

'So why would some Russian bastard with a KGB assignment choose a name like Stinnes as an operating name?'

'I wish I knew,' I said.

'Hugo Stinnes was a German capitalist, a class enemy, obsessed by the threat of world Bolshevism. What kind of joke is it for a Russian KGB man to choose that name?'

'What kind of man would choose it?' I said.

'A very, very confident Communist,' said Werner. 'A man who was so trusted by his KGB masters that he could select such a name without fear of being contaminated by it.'

'Did you only think of that now?' I asked.

'Right from the time I first heard the name it seemed a curious choice for a Communist agent. But now – now that so much depends upon his loyalty – I think of it again. And I worry.'

I said. 'Yes, the same with me, Werner.'

Werner paused and, using his little finger, scratched his bushy eyebrows. 'When the Nazi party sent Dr Goebbels to open their first office in Berlin, they used that little back cellar in Potsdamerplatz that belonged to Storch's uncle. It was a filthy hole; the Nazis called it "'the opium den". They say Storch's uncle let them have it without paying rent and in return Storch got a nice little job with the Party.'

I looked at the rain as it polished the roofs of the buildings across the courtyard. The roofs were tilted, crippled, and humpbacked, like an illustration from 'Hansel and Gretel'. My mind was not on old Herr Storch any more than Werner's was. I said, 'Why not use his real name – Sadoff – why use a German name at all? And if a German name, why Stinnes?'

'It raises a lot of questions,' said Werner as his mind went another way. 'If Stinnes was planted solely as a way of giving us false information, then the Miller woman was used only to support that trick.'

'That's not difficult to believe, Werner,' I said. 'Now that we know she wasn't drowned in the Havel, now that we know she's safe and well and working for the East German government, I've changed my mind about the whole business.'

'The whole business? Her collecting that material from the car at the big party in Wannsee? Did she want to get arrested that night when we set it up so carefully and were so pleased with ourselves? Was that confession she gave you at some length – was it all set up?'

To implicate Bret? Yes, the Miller woman made a fool of me, Werner. I believed everything she told me about the two code words. I went back to London convinced that there was another agent in London Central. I disobeyed orders. I went and talked to Brahms Four. I was convinced that someone in London Central – probably Bret – was a prime KGB agent.'

'It looked that way,' said Werner. He was being kind, as always. He could see how upset I was.

'It did to me. But no one else was fooled. You told me again and again. Dicky turned up his nose at the idea, and Silas Gaunt got angry when I suggested it. I even began to wonder if there was a big cover-up. But the truth is that they weren't fooled by her and her story, and I was.'

'Don't blame yourself, Bernard. They didn't see her. She was convincing, I know.'

'She made a fool of me. She had nicotine stains on her fingers and no cigarettes! She had inky fingers and no fountain pen! She drowns, but we find no body. How could I be so stupid! A clerk from East Berlin; yes, of course. Everyone in London Central was right and I was wrong. I feel bad about that, Werner. I have more field experience that any of those people. I should have seen through her. Instead I went around doing exactly what they wanted done.'

'It wasn't like that, Bernie, and you know it. Silas Gaunt and Dicky and the rest of them didn't argue with you or give any reasons. They wouldn't believe your theory because it would have been too inconvenient to believe it.'

'Then Posh Harry gave me documents that supported the idea that there was a mole in London Central.'

'You're not saying Posh Harry was in on it?'

'I don't think so. Posh Harry was a carefully selected go-between. They used him the way we've used him so often. That was probably Fiona's idea.'

'It's the very hell of a complicated scenario they had,' said Werner, rubbing his face. 'Are you sure that you've got it right now? Would it be worth them going to all that trouble? When you got Stinnes out of Mexico City, you nearly got killed doing it. A KGB man from the Embassy was shot.'

'That shooting was an accident, Werner. Pavel Moskvin was the one who gave me a tough tune in East Berlin. If Stinnes is a plant, then Moskvin is the man behind it. I can't prove it, of course, but Moskvin is the sort of hard-nosed Party man that Moscow has monitoring and masterminding all their important departments.'

'You think Moskvin planted him without any contacts or case officer or letter drop? You think Stinnes is all on his own?'

' "Solitaries", the Russians call them; agents whose real loyalties are known to only one or two people at the very top of the command structure. The only record of their assignment is a signed contract locked into a safe in Moscow. Sometimes when such people die, despised and unlamented, even their close relatives – wife, husband, children – aren't told the real story.'

'But Stinnes left his wife. He'd even had a fight with her.'

'Yes,' I said, 'and that convinced me that he really wanted to come over to the West. But the fight was genuine – his story false. We should have allowed for that possibility, I suppose.'

'So now you think Stinnes is a solitary?' said Werner.

'For them the solitary isn't so unusual, Werner. Communism has always glamorized secrecy; it's the Communist method; subversion, secret codes, cover names, secret inks, no agent permitted to contact more than two other agents, cells to make sure that one lost secret doesn't lead to the loss of another. All these things are not exclusively Russian, and not peculiar to the KGB; this sort of secrecy comes naturally to any Communist. It's part of the appeal that worldwide Communism has for the embittered loner. If my guess is right Moskvin is the only other person who knows the whole story. They probably didn't tell the truth to the snatch team that hit the launderette. The KGB would reason that just one extra person knowing the real story would increase the risk of us discovering that Stinnes was a plant.'