'Duff at what?'

'The rockets. They make errors.'

'What sort of errors?'

'All sorts. Magnetic errors. Bias errors, whatever those are. I don't know. That's your job, isn't it?'

But Landau's defensive surliness only emphasised his virtue as a witness.

For where he wished to shine and could not, his failure reassured them, as Walter's airy gesture of relief now testified.

'Well I think he's done terribly well,' he declared as if Landau were nowhere within earshot, flinging up his hands again, this time in a theatrical gesture of conclusion. 'He tells us what he remembers. He doesn't make things up to spin a better tale. You won't do that, will you, Niki?' he added anxiously, uncrossing his legs as if his crotch were nipping him.

'No, sir, you may rest assured.'

'And you haven't? I Mean, because sooner or later we'd find out. Then everything you've given us would lose its lustre.'

'No, sir. It's the way I told it. No more, no less.'

'I'm sure it is,' said Walter to his colleagues in a tone of simple trust as he again sat back. 'The hardest thing in our trade or anybody else's is to say "I believe." Niki's a natural source and rare as hen's teeth. If there were more of him , nobody would need us .'

'This is Johnny,' Ned explained, playing the aide-de-camp.

Johnny had wavy greying hair and a broad jaw and a file full of official-looking telegrams. With his gold watch chain and tailored charcoal suit, he might have been a foreign barmaid's- vision of an Englishman but he certainly wasn't Landau's.

'Niki, first we have to thank you, pal,' Johnny said, in lazy East Coast American. We the larger beneficiaries, his munificent tone suggested. We the majority shareholders. I'm afraid Johnny is like that. A good officer, but unable to keep his American supremacy inside its box. I sometimes -think that is the difference between American spies and our own. Americans, with their frank enjoyment of power and money, flaunt their luck. They lack the instinct to dissemble that comes so naturally to us British.

Anyway, Landau's hackles went up in a flash.

'Mind if I ask you a couple of questions?'Johnny said.

'If it's all right by Ned,' said Landau.

'Of course it is,' said Ned.

'So we're at the audio fair that night. Okay, pal?'

'Well, evening really, Johnny.'

'You escort the woman Yekaterina Orlova across the room to the top of the staircase. Where the guards are. You slay goodbye to, her.'

'She's holding my arm.'

'She's holding your arm, great. In front of the guards. You watch her down the stairs. Do you also watch her into the street, pal?'

I had not heard Johnny use 'pal' before, so I took it that he was trying to needle Landau somehow, a thing that Agency people learn from their in-house psychologists.

'Correct,' Landau snapped.

'Right into the street? Pause and think,' he suggested, with the attorney's false expansiveness.

'Into the street and out of my life.'

Johnny waited till he was sure everyone was aware that he was waiting, and Landau more aware than anybody. 'Niki, pal, we've had people stand at the top of that staircase in the last twenty-four hours. No one sees the street from the top of that staircase.'

Landau's face darkened. Not in embarrassment. In anger. 'I saw her walk down the stairs. I saw her cross the lobby to where the street is. She did not return. So unless somebody has moved the street in the last twenty-four hours, which I grant you under Stalin was always possible.

'Let's go on, shall we?' said Ned.

'See anyone walk out after her?' Johnny asked, riding Landau a little harder.

'Down the stairs or into the street?'

'Both, pal. Both.'

'No, I didn't. I didn't see her go into the street, did I, because you just told me I didn't. So why don't you answer the questions and I'll ask them?'

While Johnny sat idly back, Ned intervened. 'Niki, some things have to be very carefully examined. There's a lot at stake and Johnny has his orders.'

'I'm at stake too,' said Landau. 'My word's on the line and I don't like having it made a fool of by an American who's not even British.'

Johnny had returned to the file. 'Niki, will you please describe the security arrangements for the fair, as you yourself observed them?'

Landau took a tense breath. 'Well then,' he said, and started again. 'We had these two young uniformed policemen hanging about the hotel lobby. Those are the boys who keep the lists of all the Russians who come and go, which is normal. Then upstairs inside the hall we had the nasties. Those are the plainclothes boys. The dawdlers, they call them, the toptuny ,' he added for Johnny's enlightenment. 'After a couple of days you know the toptuny by heart. They don't buy, they don't steal the exhibits or ask for freebies and there's always one of them with the butter-blond hair, don't ask me why. We had three boys and they didn't change all week. They were the ones who watched her go down the stairs.'

'That everyone, pal?'

'As far as I know it is everyone but I'm waiting to be told I'm wrong.'

'Were you not also aware of two ladies of indeterminate age, grey-haired persons who were also present every day of the fair, came early, left late, who also didn't buy, didn't enter negotiations with any of the stand holders or exhibitors, or appear to have any legitimate purpose for attending the fair?'

'You're talking about Gert and Daisy, I suppose.'

'Excuse me?'

'There was two old biddies from the Council of Libraries. They came for the beer. Their main pleasure was whipping brochures off the stands and cadging free handouts. We christened them Pert and Daisy after a certain British radio show popular in the war years and after.'

'It did not occur to you that these ladies might also be performing a surveillance function?'

Ned's powerful hand was already out to restrain Landau but he was too late.

'Johnny,' said Landau, boiling over. 'This is Moscow, right? Moscow, Russia, pal . If I stopped to consider who had a surveillance function and who didn't, I wouldn't get out of bed in the morning and I wouldn't get into it at night. The birds in the trees are wired for all I know.'

Yet again Johnny was at his telegrams. 'You say that Yekaterina Borisovna Orlova referred to the adjoining stand of Abercrombie & Blair as having been empty on the previous day, correct?'

'I do say so, yes.'

'But you didn't see her the day before? Is that also correct?'

'It is.'

'You also say that you have an eye for a pretty lady.'

'I do, thank you, and may it long remain vigilant.'

'Don't you think you should have noticed her then?'

'I do sometimes miss one,' Landau confessed, colouring again. 'If my back is turned, if I am bent over a desk or relieving myself in the toilet, it is possible my attention may flag for a moment.'

But Johnny's nervelessness was acquiring its own authority. 'You have relatives in Poland, do you not, Mr. Landau?' The 'pal' had evidently done its work, for listening 'to the tape I noticed he had dropped it.

'I do.'

'Do you not have an elder sister highly placed in the Polish administration?'

'My sister works in the Polish Health Ministry as a hospital inspector. She is not highly placed and she is past retiring age.'

'Have you at any time directly or indirectly been the witting target of pressure or blackmail by Communist bloc agencies or third parties acting in their behalf?

Landau turned to Ned. 'A what target? My English isn't very good, I'm afraid.'

'Conscious,' said Ned with a warning smile. 'Aware. Knowing.'

'No, I haven't,' said Landau.

'In your travels to Eastern bloc countries, have you been intimate with women of those countries?'

'I've been to bed with some. I haven't been intimate.'

Like a naughty schoolboy Walter let out a squeak of choked laughter, lifting his shoulders to his neck and cupping his hand over his dreadful teeth. But Johnny soldiered doggedly on: 'Mr. Landau, have you.ever prior to this time had contacts with any intelligence agency of any hostile or friendly country anywhere?'

'Negative.'

'Have you ever sold information to any person of whatever status or profession - newspaper, enquiry agency, police, military - for any purpose, however innocuous?'

'Negative.'

'And you are not and never have been a member of a Communist party or any peace organisation or group sympathetic to its aims?'

'I'm a British subject,' Landau retorted, thrusting out his little Polish jaw.

'And you have no idea, however vague, however mistily formed, of the overall message contained in the material you handled?'

'I didn't handle it. I passed it on.'

'But you read it along the way.'

'What I could, I read. Some. Then I gave up. As I told you.'

'Why?'

'From a sense of decency, if you want to know. Something which I begin to suspect you,are not troubled by.'

But Johnny, far from blushing, was digging patiently in his file. He drew out an envelope and from the envelope a pack of postcard-size photographs which he dealt on to the table like playing-cards. Some were fuzzy, all were grainy. A few had foreground obstructions. They showed women coming down the steps of a bleak office building, some in groups, some singly. Some carried perhaps-bags, some had their heads down and carried nothing. And Landau remembered hearing that it was Moscow practice for ladies slipping out for lunchtime shopping to stuff whatever they needed into their pockets and leave their handbags lying on their desks in order to show the world they had only gone down the corridor.

'This one,' said Landau suddenly, pointing with his forefinger.

Johnny played another of his courtroom tricks. He was really too intelligent for ' all this nonsense but that didn't stop him. He looked disappointed and mighty unbelieving. He looked as if he had caught Landau in a lie. The video film shows him overacting quite outrageously. 'How can you be so damn sure, for God's sake? You never even saw her in an overcoat.'

Landau is undismayed. 'That's the lady. Katya,' he says firmly. 'I'd recognise her anywhere. Katya. She's done her hair up, but it's her. Katya. That's her bag too, plastic.' He continues staring at the photograph. 'And her wedding ring.' For a moment he seems to forget he is not alone. 'I'd do the same for her tomorrow,'he says. 'And the day after.'

Which marked the satisfactory end to Johnny's hostile examination of the witness.

As the days progressed and one enigmatic interview fol lowed another, never the same place twice, never the same people except for Ned, Landau had increasingly the feeling that things were advancing to a climax. In a sound laboratory behind Portland Place, they played him women's voices, Russians speaking Russian and Russians speaking English. But he didn't recognise Katya's. Another day, to his alarm, was devoted to money. Not theirs but Landau's. His bank statements - where the hell did they get them from? His tax returns, salary slips, savings, mortgage, endowment policy, worse than the Inland Revenue.