His gaze had not left Toby's face. 'I can imagine that Polyakov might run to quite a few reels of film, can't you? And that one of the jobs of whoever was seeing him might be to replenish his stock: take him little sealed packets. Packets of film. Unexposed film, of course, since it came from the Circus. Tell me, Toby, could you please, is Lapin a name to you?'

A lick, a frown, a smile, a forward movement of the head: 'Sure, George, I know Lapin.'

'Who ordered the lamplighter reports on Lapin destroyed?'

'I did, George.'

'On your own initiative?'

The smile broadened a fraction. 'Listen, George, I made some rungs up the ladder these days.'

'Who said Connie Sachs had to be pushed downhill?'

'Look, I think it was Percy, okay? Say it was Percy, maybe Bill. You know how it is in a big operation. Shoes to mend, pots to clean, always a thing going.' He shrugged. 'Maybe it was Roy, huh?'

'So you take orders from all of them,' said Smiley lightly. 'That's very indiscriminate of you, Toby. You should know better.'

Esterhase didn't like that at all. 'Who told you to cool off Max, Toby? Was it the same three people? Only I have to report all this to Lacon, you see. He's being awfully pressing just at the moment. He seems to have the Minister on his back. Who was it?'

'George, you been talking to the wrong guys.'

'One of us has,' Smiley agreed pleasantly. 'That's for sure. They also want to know about Westerby: just who put the muzzle on him. Was it the same person who sent you down to Sarratt with a thousand quid in notes and a brief to put Jim Prideaux's mind at rest? It's only facts I'm after, Toby, not scalps. You know me, I'm not the vindictive sort. Anyway, what's to say you're not a very loyal fellow? It's just a question of who to.' He added: 'Only they do badly want to know, you see. There's even some ugly talk of calling in the competition. Nobody wants that, do they? It's like going to solicitors when you've had a row with your wife: an irrevocable step. Who gave you the message for Jim about Tinker, Tailor? Did you know what it meant? Did you have it straight from Polyakov, was that it?'

'For God's sake,' Guillam whispered. 'Let me sweat the bastard.'

Smiley ignored him. 'Let's keep talking about Lapin. What was his job over here?'

'He worked for Polyakov.'

'His secretary in the cultural department?'

'His legman.'

'But my dear Toby: what on earth is a cultural attaché doing with his own legman?'

Esterhase's eyes were on Smiley all the time. He's like a dog, thought Guillam, he doesn't know whether to expect a kick or a bone. They flickered from Smiley's face to his hands, then back to his face, constantly checking the tell-tale places.

'Don't be damn silly, George,' Toby said carelessly. 'Polyakov is working for Moscow Centre. You know that as well as I do.' He crossed his little legs and, with a resurgence of all his former insolence, sat back in his chair and took a sip of cold tea.

Whereas Smiley, to Guillam's eye, appeared momentarily set back; from which Guillam in his confusion drily inferred that he was doubtless very pleased with himself. Perhaps because Toby was at last doing the talking.

'Come on, George,' Toby said. 'You're not a child. Think how many operations we ran this way. We buy Polyakov, okay? Polyakov's a Moscow hood but he's our joe. But he's got to pretend to his own people that he's spying on us. How else does he get away with it? How does he walk in and out of that house all day, no gorillas, no babysitters, everything so easy? He comes down to our shop so he got to take home the goodies. So we give him goodies. Chickenfeed, so he can pass it home and everyone in Moscow clap him on the back and tell him he's a big guy, happens every day.'

If Guillam's head by now was reeling with a kind of furious awe, Smiley's seemed remarkably clear.

'And that's pretty much the standard story, is it, among the four initiated?'

'Well, standard I wouldn't know,' said Esterhase, with a very Hungarian movement of the hand, a spreading of the palm and a tilting either way.

'So who is Polyakov's agent?'

The question, Guillam saw, mattered very much to Smiley: he had played the whole long hand in order to arrive at it. As Guillam waited, his eyes now on Esterhase, who was by no means so confident any more, now on Smiley's mandarin face, he realised that he too was beginning to understand the shape of Karla's clever knot, as Smiley had called it - and of his own gruelling interview with Alleline.

'What I'm asking you is very simple,' Smiley insisted. 'Notionally, who is Polyakov's agent inside the Circus? Good heavens, Toby, don't be obtuse. If Polyakov's cover for meeting you people is that he is spying on the Circus, then he must have a Circus spy, mustn't he? So who is he? He can't come back to the Embassy after a meeting with you people, loaded with reels of Circus chickenfeed, and say, "I got this from the boys." There has to be a story, and a good one at that: a whole history of courtship, recruitment, clandestine meetings, money and motive. Doesn't there? Heavens, this isn't just Polyakov's cover story: it's his lifeline. It's got to be thorough. It's got to be convincing; I'd say it was a very big issue in the game. So who is he?' Smiley enquired pleasantly. 'You? Toby Esterhase masquerades as a Circus traitor in order to keep Polyakov in business? My hat, Toby, that's worth a whole handful of medals.'

They waited while Toby thought.

'You're on a damn long road, George,' Toby said at last. 'What happens you don't reach the other end?'

'Even with Lacon behind me?'

'You bring Lacon here. Percy, too; Bill. Why you come to the little guy? Go to the big ones, pick on them.'

'I thought you were a big guy these days. You'd be a good choice for the part, Toby. Hungarian ancestry, resentment about promotion, reasonable access but not too much... quick-witted, likes money... with you as his agent, Polyakov would have a cover story that really sits up and works. The big three give you the chickenfeed, you hand it to Polyakov, Centre thinks Toby is all theirs, everyone's served, everyone's content. The only problem arises when it transpires that you've been handing Polyakov the crown jewels and getting Russian chickenfeed in return. If that should turn out to be the case, you're going to need pretty good friends. Like us. That's how my thesis runs - just to complete it. That Gerald is a Russian mole, run by Karla. And he's pulled the Circus inside out.'

Esterhase looked slightly ill. 'George, listen. If you're wrong, I don't want to be wrong too, get me?'

'But if he's right you want to be right,' Guillam suggested, in a rare interruption. 'And the sooner you're right the happier you'll be.'

'Sure,' said Toby, quite unaware of any irony. 'Sure. I mean George you got a nice idea, but Jesus, there's two sides to everyone, George, agents specially, and maybe it's you who got the wrong one. Listen: who ever called Witchcraft chickenfeed? No one. Never. It's the best. You get one guy with a big mouth starts shooting the dirt, and you dug up half London already. Get me? Look, I do what they tell me. Okay? They say act the stooge for Polyakov, I act him. Pass him this film, I pass it. I'm in a very dangerous situation,' he explained. 'For me, very dangerous indeed.'

'I'm sorry about that,' said Smiley at the window, where through a chink in the curtain he was once more studying the square. 'Must be worrying for you.'

'Extremely,' Toby agreed, 'I get ulcers, can't eat. Very bad predicament.'

For a moment to Guillam's fury they were all three joined in a sympathetic silence over Toby Esterhase's bad predicament.

'Toby, you wouldn't be lying about those babysitters, would you?' Smiley enquired, still from the window.

'George, I cross my heart, I swear you.'

'What would you use for a job like this? Cars?'

'Pavement artists. Put a bus back by the air terminal, walk them through, turn 'em over.'

'How many?'

'Eight, ten. This time of year six maybe. We got a lot ill. Christmas,' he said morosely.

'And one man alone?'

'Never. You crazy. One man! You think I run a toffee shop these days?'

Leaving the window, Smiley sat down again.

'Listen, George, that's a terrible idea you got there, you know that? I'm a patriotic fellow. Jesus,' Toby repeated.

'What is Polyakov's job in the London residency?' Smiley asked.

'Polly works solo.'

'Running his master spy inside the Circus?'

'Sure. They take him off regular work, give him a free hand so's he can handle Toby, master spy. We work it all out, hours on end I sit with him. "Listen," I say. "Bill is suspecting me, my wife is suspecting me, my kid got measles and I can't pay the doctor." All the crap that agents give you, I give it to Polly, so's he can pass it home for real.'

'And who's Merlin?'

Esterhase shook his head.

'But at least you've heard he's based in Moscow,' Smiley said. 'And a member of the Soviet Intelligence establishment, whatever else he isn't?'

'That much they tell me,' Esterhase agreed.

'Which is how Polyakov can communicate with him. In the Circus's interest of course. Secretly, without his own people becoming suspicious?'

'Sure.' Toby resumed his lament, but Smiley seemed to be listening to sounds that were not in the room.

'And Tinker, Tailor?'

'I don't know what the hell it is. I do what Percy tells me.'

'And Percy told you to square Jim Prideaux?'

'Sure. Maybe was Bill, or Roy maybe; listen, it was Roy. I got to eat, George, understand? I don't cut my throat two ways, follow me?'

'It is the perfect fix: you see that, don't you, Toby, really?' Smiley remarked in a quiet, rather distant way. 'Assuming it is a fix. It makes everyone wrong who's right: Connie Sachs, Jerry Westerby... Jim Prideaux... even Control. Silences the doubters before they've even spoken out... the permutations are infinite, once you've brought off the basic lie. Moscow Centre must be allowed to think she has an important Circus source; Whitehall on no account must get wind of the same notion. Take it to its logical conclusion and Gerald would have us strangling our own children in their beds. It would be beautiful in another context,' he remarked almost dreamily. 'Poor Toby: yes, I do see. What a time you must have been having, running between them all.'

Toby had his next speech ready: 'Naturally if there is anything I can do of a practical nature, you know me, George, I am always pleased to help, no trouble. My boys are pretty well trained, you want to borrow them, maybe we can work a deal. Naturally I have to speak to Lacon first. All I want, I want to get this thing cleared up. For the sake of the Circus, you know. That's all I want. The good of the firm. I'm a modest man, I don't want anything for myself, okay?'