'And which sort of bird are you, Erich? And how do we start teaching you how to sing?'

'I accepted your offer in good faith. I didn't promise to run your covert operations department and make it work properly.'

'What do you see as your side of the bargain?' I said.

'I give the interrogator full and truthful answers to everything he asks. But I can't tell him things I don't know. I wish you'd explain that to him.'

'Four men have died,' I said. 'You knew one of them: Ted Riley; he was with you in London. He was a personal friend of mine. People are angry.'

'I'm sorry,' said Stinnes. He didn't look very sorry, but then he never did look very anything.

'We were bounced, Erich. Both times we were bounced.'

'I don't know the full details,' he said. It was a very Russian response; he knew all the details.

'Both times we walked into a booby trap,' I said.

'Then both tunes you were a booby.'

'Don't get too damned smug,' I said, and then regretted that he'd made me angry.

'Are you a professional or have you been behind a desk too long?' He paused, and when I didn't answer he said, 'Don't toy with me, Mr Samson. You know that Rensselaer is an amateur. You know he refused to let your Operations staff plan these meetings. You know that he did it that way because he wanted to show everyone that he could be a wonderful field agent.'

It wasn't the reaction I'd expected. Stinnes showed no anger about Bret Rensselaer's actions even though they'd brought Stinnes near to being killed. In fact his interpretation of the fiasco put Bret into the role of hero – an amateur, blundering hero, but a hero nevertheless. 'Did you criticize these "amateurish" ideas?' I asked.

'Of course I did. Didn't you?'

He had me there. 'Yes,' I admitted. 'I criticized them.'

'So would anyone with half an hour's field experience. Rensselaer is a desk man. Why wasn't he ordered to use your Operations planners? I urged him to do that over and over again.'

'There were problems,' I said.

'And I can guess what the problems were,' said Stinnes. 'Your boss Rensselaer is determined to make his name before the Mis people take over my interrogation?'

'Something like that,' I said.

'He's at the dangerous age,' said Stinnes with studied contempt. 'It's the age when desk men suddenly want to grab a final chance for glory.'

There was a knock at the door and a middle-aged woman in a green apron brought in a tray of tea with buttered toast and a plate of sliced cake. 'They do you very well in here, Erich,' I said. 'Do you get this sort of stylish tea every day or only when visitors come?'

The woman smiled at me but said nothing. They were all vetted people, of course; some of the domestic help were retired clerical staff from London Central. She set out the cups and teapot and left silently. She knew that even one word can destroy the mood of an interrogation.

'Every day,' said Erich. There was a packet of five small cigars on the tray. I suppose it was his daily ration, but he seemed to have stopped smoking for there was a pile of unopened packets on the mantelpiece.

'But you still don't like it here?' His uncooperative attitude towards the interrogator was what had brought me down here. There was obviously something he didn't like.

'You trust me well enough to act on my information and risk the lives of your agents, but you keep me locked up in case I run away.' He drank some tea. 'Where is it that you think I will run to? Will I run back to Moscow and face trial?'

I was tempted to tell him how vociferously I had opposed his being brought back to Berwick House, but that wasn't the way to do it. And in any case, I didn't want him to know how little effect my opinions had upon London Central's top-floor decisions. 'So what sort of bird are you, Erich? You haven't answered that one yet.'

'Let me out of here and I'll show you,' he said. 'Let me do what Rensselaer failed to do.'

'Penetrate the Cambridge network?'

'They'll trust me.'

'It's risky, Erich.'

'The Cambridge network is the best thing I brought over to you. It's what delayed me in Mexico City. It's what forced me to go back to Berlin before coming over to you. Do you have any idea what risks I took to get enough information to penetrate that network?'

'Tell me.'

It was a sardonic reaction to his plea and he knew it. He said, 'And now you want to throw it away. Well, it's your loss.'

'Then why do you care?'

'Only because you are determined to blame me for disasters of your own making. Why should I be blamed? Why should I be punished? I don't want to spend month after month locked up in this place.'

'I thought you liked it,' I said.

'It's comfortable enough, but I'm a prisoner here. I want to live like a human being. I want to spend some of that money. I want to… I want to do all sorts of things.'

'You want to see Zena Volkmann? Is that what you were going to say?'

'Have you seen her?'

'Yes,' I said.

'Did she ask about me?'

'She thinks she did all the work, I got all the credit, and you got all the money.'

'Is that what she said?'

'More or less.'

'I suppose it's true.' He took off his glasses and polished them carefully.

'I don't know that she did all the work, and I certainly didn't get all the credit. Other than that, I suppose it's true.'

He looked at me but didn't smite at my allegation. 'You needn't worry. If I am freed, I won't go rushing off to find her.'

'The love has cooled?'

'I'm fond of her. But she is another man's wife. I no longer have the stamina for that sort of love affair.'

'But you have the stamina to try breaking into the Cambridge net?'

'Because it's the only way I'll ever be able to get free of you people.'

'By giving us proof positive of your loyalty to us?'

'As I've told you, that network is the best prize I can offer you. Surely even you English will not want to keep me locked up after I deliver them to you?' These were his own agents, yet he said it without any sign of emotion. He was a cold-blooded animal.

'There is the problem of protecting you, Erich. You are a big investment. They put a bomb under your car last week.'

'That wasn't intended for me. That was an accident. Surely you don't believe that they identified me?' He leaned back in the sofa and grasped his hands together and cracked the knuckles. It was an old man's gesture that didn't fit my picture of him. Was it this captivity that was ageing him? He was a 'street man' – his whole career had been based upon dealing with people. If he was allowed to try breaking the Cambridge net, at least he'd be doing the thing he was best at. Perhaps all betrayals – marital, professional and political -are motivated by the drive to do what you're best at, no matter whom you're doing it for.

'You seem very certain,' I said.

'I'm not paranoid, if that's what you mean.'

I left it like that for a moment and drank some tea. 'You're not smoking these days, I notice.' I picked up the packet of cheroots from the tray and sniffed them. I hadn't smoked for ages. I put the cheroots down again, but it wasn't easy.

'I don't feel like smoking,' he said. 'It's a good chance for me to give up altogether.'

I poured myself some tea and drank it without milk or sugar the way he drank his; it was awful. 'How would you start?' I didn't have to explain what I meant. The idea of Stinnes trying to crack a Soviet network using his own methods was uppermost in both our minds.

'First, I've got to have my freedom. I can't work if you are going to have someone watching me night and day. I must be able to go to them completely clear of all your strings. You understand?'

'They're alarmed now,' I said. They must have been in touch with Moscow. Moscow might have told them about you.'