Afterwards, in the dusty little corners where London's secret servants drink together, there was argument abort where the Dolphin case history should really begin. One crowd, led by a blimpish fellow in charge of microphone transcription, went so far as to claim that the fitting date was sixty years ago when 'that arch-cad Bill Haydon' teas born into the world under a treacherous star. Haydon's very name struck a chill into them. It does so even today. For it was this same Haydon who, while still at Oxford, was recruited by Karla the Russian as a 'mole', or 'sleeper', or in English, agent of penetration, to work against them. And who with Karla's guidance entered their ranks and spied on them for thirty years or more. And whose eventual discovery - thus the line of reasoning - brought the British so low that they were forced into a fatal dependence upon their American sister service, whom obey called in their own strange jargon 'the Cousins'. The Cousins changed the game entirely, said the blimpish fellow: much as he might have deplored power tennis or bodyline bowling. And ruined it too, said his seconds.

To less flowery minds, the true genesis was Haydon's unmasking by George Smiley and Smiley's consequent appointment as a caretaker chief of the betrayed service, which occurred in the late November of 1973. Once George had got Karla under his skin, they said, there was no stopping him. The rest was inevitable, they said. Poor old George: but what a mind under all that burden!

One scholarly soul, a researcher of some sort, in the jargon a 'burrower', even insisted, in his cups, upon January 26th 1841 as the natural date, when a certain captain Elliot of the Royal Navy took a landing party to fog-laden rock called Hong Kong at the mouth of the pearl River and a few days later proclaimed it a British colony. With Elliot's arrival, said the scholar, Hong Kong became the headquarters of Britain's opium trade to China and in consequence one of the pillars of the imperial economy. If the British had not invented the opium market - he said, not entirely serious -then there would have been no case, no ploy, no dividend: and therefore no renaissance of the Circus following Bill Haydon's traitorous depredations.

Whereas the hard men - the grounded fieldmen, the trainers and the case officers who made their own murmured caucus always - they saw the question solely in operational terms. They pointed to Smiley's deft footwork in tracking down Karla's paymaster in Vientiane; to Smiley's handling of the girl's parents; and to his wheeling and dealing with the reluctant barons of Whitehall, who held the operational purse strings, and dealt out rights and permissions in the secret world. Above all, to the wonderful moment when he turned the operation round on its own axis. For these pros, the Dolphin case was a victory of technique. Nothing more. They saw the shotgun marriage with the Cousins as just another skilful bit of tradecraft in a long and delicate poker game. As to the final outcome: to hell. The king is dead; so long live the next one.

The debate continues wherever old comrades meet, though the name of Jerry Westerby, understandably, is seldom mentioned. Occasionally, it is true, somebody does, out of foolhardiness or sentiment or plain forgetfulness, dredge it up, and there is atmosphere for a moment; but it passes. Only the other day a young probationer just out of the Circus's refurbished training school at Sarratt - in the jargon again, 'the Nursery' - piped it out in the under-thirties bar, for instance. A watered-down version of the Dolphin case had recently been introduced at Sarratt as material for syndicate discussion, even playlets, and the poor boy, still very green, was fairly brimming with excitement to discover he was in the know: 'But my God,' he protested, enjoying the kind of fool's freedom sometimes granted to naval midshipmen in the wardroom, 'my God, why does nobody seem to recognise Westerby's part in the affair? If anybody carried the load, it was Jerry Westerby. He was the spearhead. Well, wasn't he? Frankly?' Except, of course, he did not utter the name 'Westerby', nor 'Jerry' either, not least because he did not know them; but used instead the cryptonym allocated to Jerry for the duration of the case.

Peter Guillam fielded this loose ball. Guillam is tall and tough and graceful, and probationers awaiting first posting tend to look up to him as some sort of Greek god.

'Westerby was the stick that poked the fire,' he declared curtly, ending the silence. 'Any fieldman would have done as well, some a damn sight better.'

When the boy still did not take the hint, Guillam rose and went over to him and, very pale, snapped into his ear that he should fetch himself another drink, if he could hold it, and thereafter guard his tongue for several days or weeks. Whereupon, the conversation returned once more to the topic of dear old George Smiley, surely the last of the true greats, and what was he doing with himself these days, back in retirement? So many lives he had led; so much to recollect in tranquillity, they agreed.

'George went five times round the moon to our one,' someone declared loyally, a woman.

Ten times, they agreed. Twenty! Fifty! With hyperbole, Westerby's shadow mercifully receded. As in a sense, so did George Smiley's. Well, George had a marvellous innings, they would say. At his age what could you expect?

Perhaps a more realistic point of departure is a certain typhoon Saturday in mid-1974, three o'clock in the afternoon, when Hong Kong lay battened down waiting for the next onslaught. In the bar of the Foreign Correspondents' Club, a score of journalists, mainly from former British colonies - Australian, Canadian, American -fooled and drank in a mood of violent idleness, a chorus without a hero. Thirteen floors below them, the old trams and double deckers were caked in the mud-brown sweat of building dust and smuts from the chimney-stacks in Kowloon. The tiny ponds outside the highrise hotels prickled with slow, subversive rain. And in the men's room, which provided the Club's best view of the harbour, young Luke the Californian was ducking his face into the handbasin, washing the blood from his mouth.

Luke was a wayward, gangling tennis player, an old man of twenty-seven who until the American pullout had been the star turn in his magazine's Saigon stable of war reporters. When you knew he played tennis it was hard to think of him doing anything else, even drinking. You imagined him at the net, uncoiling and smashing everything to kingdom come; or serving aces between double faults. His mind, as he sucked and spat, was fragmented by drink and mild concussion - Luke would probably have used the war-word 'fragged' -into several lucid parts. One part was occupied with a Wanchai bar girl called Ella for whose sake he had punched the pig policeman on the jaw and suffered the inevitable consequences: with the minimum necessary force, the said Superintendent Rockhurst, known otherwise as the Rocker, who was this minute relaxing in a corner of the bar after his exertions, had knocked him cold and kicked him smartly in the ribs. Another part of his mind was on something his Chinese landlord had said to him this morning when he called to complain of the noise of Luke's gramophone, and had stayed to drink a beer.

A scoop of some sort definitely. But what sort?

He retched again, then peered out of the window. The junks were lashed behind the barriers and the Star Ferry had stopped running. A veteran British frigate lay at anchor and Club rumours said Whitehall was selling it.

'Should be putting to sea,' he muttered confusedly, recalling some bit of naval lore he had picked up in his travels. 'Frigates put to sea in typhoons. Yes, sir.'

The hills were slate under the stacks of black cloudbank. Six months ago the sight would have had him cooing with pleasure. The harbour, the din, even the skyscraper shanties that clambered from the sea's edge upward to the Peak: after Saigon, Luke had ravenously embraced the whole scene. But all he saw today was a smug, rich British rock run by a bunch of plum-throated traders whose horizons went no further than their belly-lines. The Colony had therefore become for him exactly what it was already for the rest of the journalists: an airfield, a telephone, a laundry, a bed. Occasionally - but never for long - a woman.

Where even experience had to be imported. As to the wars which for so long had been his addiction: they were as remote from Hong Kong as they were from London or New York. Only the Stock Exchange showed a token sensibility, and on Saturdays it was closed anyway.

'Think you're going to live, ace?' asked the shaggy Canadian cowboy, coming to the stall beside him. The two men had shared the pleasures of the Tet offensive.

'Thank you, dear, I feel perfectly topping,' Luke replied, in his most exalted English accent.

Luke decided it really was important for him to remember what Jake Chiu had said to him over the beer this morning, and suddenly like a gift from Heaven it came to him.

'I remember!' he shouted. 'Jesus, cowboy, I remember! Luke, you remember! My brain! It works! Folks, give ear to Luke!'

'Forget it,' the cowboy advised. 'That's badland out there today, ace. Whatever it is, forget it.'

But Luke kicked open the door and charged into the bar, arms flung wide.

'Hey! Hey! Folks!'

Not a head turned. Luke cupped his hands to his mouth.

'Listen you drunken bums, I got news. This is fantastic. Two bottles of Scotch a day and a brain like a razor. Someone give me a bell.'

Finding none, he grabbed a tankard and hammered it on the bar rail, spilling the beer. Even then, only the dwarf paid him the slightest notice.

'So what's happened, Lukie?' whined the dwarf, in his queeny Greenwich Village drawl. 'Has Big Moo gotten hiccups again? I can't bear it.'

Big Moo was Club jargon for the Governor and the dwarf was Luke's chief of bureau. He was a pouchy, sullen creature with disordered hair that swept in black strands over his face, and a silent way of popping up beside you. A year back, two Frenchmen, otherwise rarely seen here, had nearly killed him for a chance remark he had made on the origins of the mess in Vietnam. They took him to the lift, broke his jaw and several of his ribs, then dumped him in a heap on the ground floor and came back to finish their drinks. Soon afterwards the Australians did a similar job on him when he made a silly accusation about their token military involvement in the war. He suggested that Canberra had done a deal with President Johnson to keep the Australian boys in Vung Tau which was a picnic, while the Americans did the real fighting elsewhere. Unlike the French, the Australians didn't even bother to use the lift. They just beat the hell out of the dwarf where he stood, and when he fell they added a little more of the same. After that, he learned when to keep clear of certain people in Hong Kong. In times of persistent fog, for instance. Or when the water was cut to four hours a day. Or on a typhoon Saturday.