'Why the devil did she choose Tarr?' Lacon muttered at last, fiddling his long fingers. 'Of all the people in the world to choose for a confessor, I can imagine none more miserably unsuitable.'

'I'm afraid you'll have to ask a woman that question, not us,' said Smiley, wondering again where Immingham was.

'Oh indeed,' Lacon agreed lavishly. 'All that's a complete mystery. I'm seeing the Minister at eleven,' he confided in a lower tone, 'I have to put him in the picture. Your parliamentary cousin,' he added, forcing an intimate joke.

'Ann's cousin actually,' Smiley corrected him, in the same absent tone. 'Far removed I may add, but cousin for all that.' 'And Bill Haydon is also Ann's cousin? Our distinguished Head of London station.' They had played this game before as well.

'By a different route, yes, Bill is also her cousin.' He added quite uselessly: 'She comes from an old family with a strong political tradition. With time it's rather spread.'

'The tradition?' - Lacon loved to nail an ambiguity.

'The family.'

Beyond the trees, Smiley thought, cars are passing. Beyond the trees lies a whole world, but Lacon had this red castle and a sense of Christian ethic that promises him no reward except a knighthood, the respect of his peers, a fat pension and a couple of charitable directorships in the City.

'Anyway I'm seeing him at eleven.' Lacon had jerked to his feet and they were walking again. Smiley caught the name 'Ellis' floating backward to him on the leafy morning air. For a moment, as in the car with Guillam, an odd nervousness overcame him.

'After all,' Lacon was saying, 'we both held perfectly honourable positions. You felt that Ellis had been betrayed and you wanted a witch-hunt. My Minister and I felt there had been gross incompetence on the part of Control - a view which to put it mildly the Foreign Office shared - and we wanted a new broom.'

'Oh I quite understand your dilemma,' said Smiley, more to himself than to Lacon.

'I'm glad. And don't forget, George: you were Control's man. Control preferred you to Haydon and when he lost his grip towards the end and launched that whole extraordinary adventure it was you who fronted for him. No one but you, George. It's not every day that the head of one's secret service embarks on a private war against the Czechs.' It was clear that the memory still smarted. 'In other circumstances I suppose Haydon might have gone to the wall, but you were in the hot seat and-'

'And Percy Alleline was the Minister's man,' said Smiley, mildly enough for Lacon to slow himself and listen.

'It wasn't as if you had a suspect, you know! You didn't point the finger at anyone! A directionless enquiry can be extraordinarily destructive!'

'Whereas a new broom sweeps cleaner.'

'Percy Alleline? All in all he has done extremely well. He has produced intelligence instead of scandal, he has stuck to the letter of his charter and won the trust of his customers. He has not yet, to my knowledge, invaded Czechoslovak territory.'

'With Bill Haydon to field for him, who wouldn't?'

'Control, for one,' said Lacon, with punch. They had drawn up at an empty swimming pool and now stood staring into the deep end. From its grimy depths Smiley fancied he heard again the insinuating tones of Roddy Martindale: 'Little reading rooms at the Admiralty, little committees popping up with funny names...'

'Is that special source of Percy's still running?' Smiley enquired. 'The Witchcraft material or whatever it's called these days?'

'I didn't know you were on the list,' Lacon said, not at all pleased. 'Since you ask, yes. Source Merlin's our mainstay and Witchcraft is still the name of his product. The Circus hasn't turned in such good material for years. Since I can remember, in fact.'

'And still subject to all that special handling?'

'Certainly, and now that this has happened I've no doubt that we shall take even more rigorous precautions.'

'I wouldn't do that if I were you. Gerald might smell a rat.'

'That's the point, isn't it?' Lacon observed quickly. His strength was improbable, Smiley reflected. One minute he was like a thin, drooping boxer whose gloves were too big for his wrists; the next he had reached out and rocked you against the ropes, and was surveying you with Christian compassion. 'We can't move. We can't investigate because all the instruments of enquiry are in the Circus's hands, perhaps in the mole Gerald's. We can't watch, or listen, or open mail. To do any one of those things would require the resources of Esterhase's lamplighters, and Esterhase, like anyone else, must be suspect. We can't interrogate, we can't take steps to limit a particular person's access to delicate secrets. To do any of these things would be to run the risk of alarming the mole. It's the oldest question of all, George. Who can spy on the spies? Who can smell out the fox without running with him?' He made an awful stab at humour: 'Mole, rather,' he said, in a confiding aside.

In a fit of energy Smiley had broken away and was pounding ahead of Lacon down the path that led towards the paddock.

'Then go to the competition,' he called. 'Go to the security people. They're the experts, they'll do you a job.'

'The Minister won't have that. You know perfectly well how he and Alleline feel about the competition. Rightly too, if I may say so. A lot of ex-colonial administrators ploughing through Circus papers: you might as well bring in the army to investigate the navy!'

'That's no comparison at all,' Smiley objected.

But Lacon as a good civil servant had his second metaphor ready: 'Very well, the Minister would rather live with a damp roof than see his castle pulled down by outsiders. Does that satisfy you? He has a perfectly good point, George. We do have agents in the field and I wouldn't give much for their chances once the security gentlemen barge in.'

Now it was Smiley's turn to slow down.

'How many?'

'Six hundred, give or take a few.'

'And behind the Curtain?'

'We budget for a hundred and twenty.' With numbers, with facts of all sorts, Lacon never faltered. They were the gold he worked with, wrested from the grey bureaucratic earth. 'So far as I can make out from the financial returns, almost all of them are presently active.' He took a long bound. 'So I can tell him you'll do it, can I?' he sang, quite casually, as if the question were mere formality, tick the appropriate box. 'You'll take the job, clean the stables? Go backwards, go forwards, do whatever is necessary? It's your generation after all. Your legacy.' Smiley had pushed open the paddock gate and slammed it behind him. They were facing each other over its rickety frame. Lacon, slightly pink, wore a dependent smile.

'Why do I say Ellis?' he asked conversationally. 'Why do I talk about the Ellis affair when the poor man's name was Prideaux?'

'Ellis was his workname.'

'Of course. So many scandals in those days, one forgets the details.' Hiatus. Swinging of the right forearm. Lunge. 'And he was Haydon's friend, not yours?'

'They were at Oxford together before the war.'

'And stablemates in the Circus during and after. The famous Haydon-Prideaux partnership. My predecessor spoke of it interminably.' He repeated: 'But you were never close to him?'

'To Prideaux? No.'

'Not a cousin, I mean?'

'For Heaven's sake,' Smiley breathed.

Lacon grew suddenly awkward again, but a dogged purpose kept his gaze on Smiley. 'And there's no emotional or other reason which you feel might debar you from the assignment? You must speak up, George,' he insisted anxiously, as if speaking up were the last thing he wanted. He waited a fraction, then threw it all away: 'Though I see no real case. There's always a part of us that belongs to the public domain, isn't there? The social contract cuts both ways, you always knew that I'm sure. So did Prideaux.'

'What does that mean?'

'Well, good Lord, he was shot, George. A bullet in the back is held to be quite a sacrifice, isn't it, even in your world?' Alone, Smiley stood at the further end of the paddock, under the dripping trees, trying to make sense of his emotions while he reached for breath. Like an old illness, his anger had taken him by surprise. Ever since his retirement he had been denying its existence, steering clear of anything that could touch it off: newspapers, former colleagues, gossip of the Martindale sort. After a lifetime of living by his wits and his considerable memory, he had given himself full-time to the profession of forgetting. He had forced himself to pursue scholarly interests which had served him well enough as a distraction while he was at the Circus, but now that he was unemployed were nothing, absolutely nothing. He could have shouted: Nothing!

'Burn the lot,' Ann had suggested helpfully, referring to his books. 'Set fire to the house. But don't rot.'

If by rot, she meant conform, she was right to read that as his aim. He had tried, really tried, as he approached what the insurance advertisements were pleased to call the evening of his life, to be all that a model rentier should be; though no one, least of all Ann, thanked him for the effort. Each morning as he got out of bed, each evening as he went back to it usually alone, he had reminded himself that he never was and never had been indispensable. He had schooled himself to admit that in those last wretched months of Control's career, when disasters followed one another with heady speed, he had been guilty of seeing things out of proportion. And if the old professional Adam rebelled in him now and then and said: You know the place went bad, you know Jim Prideaux was betrayed - and what more eloquent testimony is there than a bullet, two bullets in the back? - Well, he had replied, suppose he did? And suppose he was right? 'It is sheer vanity to believe that one, fat, middle-aged spy is the only person capable of holding the world together,' he would tell himself. And other times: 'I never heard of anyone yet who left the Circus without some unfinished business.'

Only Ann, though she could not read his workings, refused to accept his findings. She was quite passionate, in fact, as only women can be on matters of business, really driving him to go back, take up where he had left off, never to veer aside in favour of the easy arguments. Not of course that she knew anything, but what woman was ever stopped by a want of information? She felt. And despised him for not acting in accordance with her feelings.

And now, at the very moment when he was near enough beginning to believe his own dogma, a feat made no easier by Ann's infatuation for an out-of-work actor, what happens but that the assembled ghosts of his past - Lacon, Control, Karla, Alleline, Esterhase, Bland, and finally Bill Haydon himself - barge into his cell and cheerfully inform him, as they drag him back to this same garden, that everything which he had been calling vanity is truth?