'It seemed a clever idea at the time,' said Fiona calmly. Despite the phrase there was nothing in her voice to suggest it wasn't a clever idea now.

'Who thought it was a clever idea?'

'Your surprise, or let's rather say astonishment… Your anger, indignation and obvious bewilderment protected me, Bernard.'

'I asked you, "Who thought it was a clever idea?" '

'I wanted to tell you everything, darling. I insisted upon it at first. I wanted you in at the briefings and the preparation. The original idea was that you would be my case officer, but then it became obvious that there couldn't be a case officer in the ordinary sense of that term. There was no question of frequent regular contact.'

'So who decided otherwise?'

'At the beginning the D-G was against the whole scheme. He gave it no more than a twenty-five per cent chance of coming off.'

'I would have given it less than that.'

'The D-G made it a condition that you would not be told.'

'The D-G… Sir Henry?'

'He has his good days as well as his bad ones.'

'So the more fuss I kicked up the better?'

'At first, yes. And it certainly worked,' said Fiona. 'In the first few weeks Moscow put you under their priority surveillance; they watched you with the greatest interest. They even had one of their psychological behaviour experts write a report on you. Erich Stinnes got hold of a copy and I read it. It said that no actor could have put on a performance like yours. And of course they were right. It was your behaviour that finally convinced them that I was really theirs.'

'Didn't they guess the truth? That you acted without telling me?'

The Soviet Union may have women fighter pilots and crane operators but marriage is a sacred institution here. Thanks to the millions of war casualties, Marx's views on marriage – like his views on a lot of other things – have been shelved indefinitely. Wives in the USSR do as their husbands say.'

I looked at her without speaking. She smiled. I wondered why I had been surprised by this whole business. Fiona: cultured privileged daughter of philistine nouveau riche father; exceptional Oxford graduate who studied Russian at the Sorbonne. She joins the Department and marries a man who never went to college and whose sole claim to any sort of respect is his reputation as a field agent. Why wouldn't such a person prove to be the ultimate exponent of women's emancipation? Why wouldn't such a woman want to be an even better field agent, at whatever the cost to me and the children and everyone else around her?

'When did all this start?' I asked.

'Long ago,' she replied airily.

'September 1978?' That was the night of one of those 'Baader-Meinhof panics. The content of a Russian army signals intercept got back to Karlshorst so quickly that everyone thought we had a superspy sitting in Operations. She nodded. 'You leaked that intercepted signal to them? So you were working both sides already.' I took a moment or two to recollect what had happened. 'Joe Brody was called in to handle the subsequent investigation, just in order to calm the anxiety in American hearts. In some way or other you slipped past him. But with you in the clear the blame was put upon Werner Volkmann and he wasn't even given a chance to defend himself. Frank wouldn't use him any more, and Werner took it badly.'

'That's right,' she said and bit her lip. She'd always disliked Werner, or at least dismissed him as something of a simpleton. Had some feeling of guilt, at the part she'd played in framing him, seeded that dislike? She said, 'Then when they opened an orange file on Trent the blame was put on him,'

' Trent was killed,' I said.

She had her answer ready. Her voice was calm and conciliatory. 'Yes, killed by your friend Rolf Mauser. With a gun he borrowed from you. You can't implicate the Department in Trent 's death.'

'But how convenient it was. Trent took his secret to the grave, and the secret was that he didn't give that intercept to the Russians.'

She said nothing.

I said, 'Were you approached at Oxford? Was it that long ago?'

'By the Department? Yes.'

So that was it. Those stories of her joining Marxist groups at college were true but it had been done to try her out. Of more personal concern was the way she'd let me recommend her for a job with the Department. That had all been a ruse: a way of covering her previous service. She must have been in regular contact with the KGB by then. Getting the SIS job would have made her case officer feel ecstatic. I could see the long-term planning that had made her so convincing as a Russian agent. It made me feel a damned fool but I controlled my anger. 'Who else knew?' I asked.

'I can't tell you that, darling.'

'Who else?'

'No one else. Not Coordination, not Central Funding, not Internal Security, not even the Deputy.'

'The D-G knew,' I persisted.

'No one working there now,' she said pedantically. That was the condition the D-G made. No one!'

'You made my life hell,' I told her gently.

'I thought you'd be proud of me.'

'I am,' I said, trying to put some feeling into my words. 'I really am. But now is the time to pull out. Come back to Vienna with me. Your KGB identification plus my special identity card would get us through the control. We could catch an evening plane to London.'

'I'm not sure that it would, Bernard. The crossing points are all on the computer nowadays. Believe me, it's something I know about.' I knew that tone of voice; there was no arguing with it.

She'd heard me say a million times that field agents have to have the last word in such matters. I'd always used my experience as a field agent to have the final decision. Now my wife had proved to be the most amazing field agent of all. She'd moved into the top echelon of the East's espionage network and fooled them all. I was in no position to argue with her.

Lightly, as if to turn the conversation to trivial matters, she said, 'I will have to make sure the computer gives the okay when I come. London have promised me something special in the way of papers.'

'They have good people here,' I said without really believing it. I wondered if her forged papers were being prepared by Staiger; done by the same crooks whom he got to fake his stamps and covers.

'I know.'

'And Erich Stinnes too?' When the history of the Department is written no fiasco of the recent past will demonstrate its capacity for vacillation and confusion better than the way in which Stinnes was handled. Stinnes was a slippery customer, a real old-time KGB officer. He'd said he wanted to defect to us, then doubts arose on both sides until Stinnes was categorized as hostile and imprisoned by us. He eventually went back to the East as part of an exchange.

'Stinnes is kept entirely separate. That's the way it was planned.' She paused and changed the subject slightly. 'When you got rid of that brute Moskvin you removed my greatest danger. He suspected the truth.'

'He took a Russian bullet too. One of your people shot him. Did you know that?'

She gave a frosty smile.

I didn't want to leave it like that. 'I wish…'

She raised a hand to silence any recrimination from me and said, 'We've only got a few minutes. The car must leave at four. I must be back in Prague. There's this damned security conference tomorrow and I have to be briefed.' The dog barked again, more fiercely this time, and the barking stopped with a shrill yelp, as if the dog had been dealt a blow.

'Yes, four o'clock. I understand.'

'So they did tell you something?'

It was a feeble joke but I smiled and apologetically said, 'We left Vienna early but there was the Haydn Festival, and the road…'

'I know,' she said. 'It's always like that when it's really important. You used to say that.'

'When I was late?'