"It's Major Maxim now, isn't it, sir? I don't suppose you remember me." There was a sly challenge in that: an Army officer is supposed to remember people. The man was very square and solid, with short fair hair, a snub nose and a slight Welsh accent.

"Ferris," Maxim said. "Sergeant Bill Ferris. You were instructing at Hereford when I started my first tour with SAS. Parachute Regiment, weren't you?"

Ferris was delighted. "I told you Mr Maxim never forgot a face, didn't I"? They shook hands. "It must be all of twelve years ago, at that."

Maxim tapped Ferris's stomach. "That's something I don't remember."

Ferris grinned again. "In Special Branch we don't do so much doubling up and down hills as I used to." He introduced Maxim to the other policemen; most of them were sergeants, and Ferris the only inspector. They shook hands politely, then faded back to their work, one of them taking Ferris's place down by the piano. They were pulling at the floorboards, probing the walls with large needles, carefully dismantling the standard lamps.

"Take your pick, sir," Ferris waved his hand at a collection of objects on a small table. There was a torch battery, a talcum powder tin, a large table lighter, silver cigarette box and a few others.

Maxim hesitated. "If I choose right, do I get my hand blown off?"

"This isn't Aden, sir. Nor Londonderry. Just pick one."

Maxim chose the talcum tin. Ferris unscrewed the cap, sprinkled a little powder to prove it worked, then screwed the cap back on and gave it an extra twist and push. The tin slid apart, a tin within a tin. The powder was held in a narrow central compartment, with empty hiding places on either side.

"Beautiful work," Ferris purred. "Beautiful. Moscow Centre does a lovely job. But of course-" he went on showing the secret compartments in the torch battery, the table lighter and all the others; "-they've always had a tradition of craftsmanship. I don't say Russian make good artists, mind. But they're craftsmen. I read the other day about a Russian who carves little temples and things out of bits of ivory that you can only see under a really powerful glass. He makes a cut in between his heartbeats, the article said, to keep his hand steady. They give his work to visiting VIP's and people."

As a policeman, Ferris had flowered surprisingly. Maxim remembered him as a very plodding instructor in communications. And that reminded him. "Have you found any radio gear?"

Ferris looked up, shocked. "Oh no, sir, Moscow Centre wouldn't use radio these days. Not in this country, anyway."

Maxim felt he'd made an indecent suggestion by mistake. "Sorry. But then how did he get in touch with his friends in Kensington Palace Gardens?"

"I thought you knew something about that already, sir." Ferris looked sly again. "The dead letter box on the train, wasn't it?"

"That was only a one-way street. He wasn't sending anything."

"Then any other way. There could be a thousand. He could think of a few for himself, I expect, him being so much in the business already." Maxim realised that Special Branch wasn't totally dismayed at MI5 being caught in the wrong bed. "Of course, most of what he'd be passing on would be film, undeveloped 110-size film cassettes. You see?" He held up the talcum tin again. "Just the right size, made for it. He'd photograph some documents in his office, then leave this at some drop. It isn't suspicious to own one of those pocket cameras, now everybody's got them. But he couldn't exactly take it down to the corner shop to be developed, now could he, sir?"

"Hardly."

"The trouble we take to make it easy for other people's spies." Ferris sighed. "We invent these cameras and button-sized microphones and put copying machines in every office… Did you know that in Russia every typewriter has to be registered with the police and they take a sample page from it, in case you start spreading those samizdats?'

"Really?" Maxim knew that already.

"It is a fact. And-" Then one of the policemen called him over. Ferris said. "Excuse me," and went back to the suspect floorboard beside the piano.

Maxim watched for a while, then got bored. The operation had the leisurely thoroughness of an old lady doing embroidery; a proper house search like this could easily last a week. He drifted back through the dining room to the corridor, where the other two policemen had finished rolling up the carpet. They looked at him, but said nothing.

If the Massons had had children, they didn't live at home any more. There were four possible bedrooms, one of which had been turned into a study and another which had no clothes or character and was obviously a spare room. Then husband and wife each had a room, with a linking door. He was fumbling among the clothes in Rex Masson's built-in cupboard when Agnes came quietly up behind him.

"How are you doing, Sherlock?"

"You know my methods – and they don't seem to do any good. I can tell he went in a hurry. I wouldn't walk out on a wardrobe like this." The clothes were all good quality, most of them tailored, and the shoes expensive.

"If you're moonlighting for Moscow you can afford to be a snappy dresser. I doubt he'd risk even coming home. Just ring her and tell her to meet him. He can't have known how much time he had. She left behind a lot of good stuff, too."

"Was she in it with him?" Maxim went on rummaging.

"You can't tell. All that gimmickry – the talcum tin and the cigarette lighter and so on – that came from his room or the study. Philby's wife didn't know. But you get some husband-and-wife teams as well."

Masson obviously had the habit of putting tickets – theatre, car-park, cinema – into his outside breast pocket. Half the jackets in the closet had some. And once, in his first Latin lesson, the young Harry Maxim had noticed that the adjectives had the same endings as the nouns to which they applied. Perhaps he, he alone, had spotted this and for him Latin was going to be easy! Perhaps putting ticket stubs in your breast pocket was a sure sign of treachery. Life should be that simple.

"D'you notice anything about the house?" Agnes asked. "Taking everything together?"

Maxim stopped and looked around and tried to remember. Overall, the house was rather dark and worn; the furniture wasn't expensive, the central heating radiators were the heavy old-fashioned kind you found in barracks and schools – big enough to sit on (it was supposed to give you piles or chilblains, he couldn't remember which). But the clothes…

"He spent his money on things he could take with him," he decided. "Not on the house. What car did he have?"

"A five-year-old Renault 12. She had an eight-year-old Mini. That's right: he was always going home to Moscow in the end."

"I suppose they always have to."

"Sometimes faster than they expect," Agnes said grimly. "Those bastards are not going to like the Moscow clothing shops."

In fact, the house did have a front door, but as it was set at ninety degrees to the sensible, it was invisible from the drive. And since the uniformed policeman wasn't guarding the house in any serious sense, Mrs Barbara Masson walked up to the door and let herself in on her key before anybody had seen her.

She stood in a tiny hallway, lined with coats, between the two big rooms and asked loudly: "And just who on earth are all of you?"

Agnes came quickly across the dining-room. "Hello, Barbara. We're us. Plus Special Branch, of course."

"I do hope, Agnes Algar, that at least you've got a search warrant."

"Oh yes, we're all being very legal. We even brought our own tea and sugar and milk. That's standard procedure on occasions like this."

Mrs Masson put down the suitcase she had in one hand and the airline bag she had in the other and slowly knelt down between them and began to cry and cry and cry.