Maxim found it difficult to begin. "I haven't mentioned it to anyone else… There was a girl in Professor Tyler's room…"

"From what I hear tell, there's usually a girl in Professor Tyler's room. There certainly was at Princeton."

"You provided this one."

Brock narrowed his eyes. "Sure."

"And there was a newspaper reporter staying here."

"That's right. He got one of the other girls. Were you thinking I was setting up Professor Tyler for a nice dirty story?"

"I was just asking."

For a moment, Brock was about to get angry. Then he shook his head and said gently: "Harry, it's a long time since I told anybody about the birds and the bees, but I'll try… Fact one: we aren't going to get any British contract for the mortar. We never were; I could smell that the moment we got here. I assume there's a political reason, but I don't know why.

"But so what?" He took a gulp of coffee. "There's no winning in being a bad loser. Next year maybe we'll sell you the biodegradable anti-personnel mine, or something new in rifle grenades. I could talk your ass off about what we've got coming up there.

"I believe I will have something stronger." He filled up his coffee with Irish whiskey. "Fact two: if you think I was setting up your Professor for a little blackmail, you've blown your tiny Neanderthal mind. For one thing, I really do admire him as a military thinker. Sure, knowing him could be good for trade – or it could be no good at all, particularly if your prime minister loses the next election. Then the Professor would be back in the wilds of Cambridge, England, without any say in policy.

"But-" he stood up and made slow mark-time movements, stretching the stiffness out of his legs. He must have been sitting there a long time, Maxim realised; "-but let me tell you something that would be very bad for trade indeed: any whisper that we went in for blackmail. Giving big commissions, sweeteners, call it bribery if you like – yes, that happens all the time. In most of the countries we do it, there isn't even a word for it: it's just a way of life. And it hasn't hurt Lockheed or Dassault or all the others that there's a rumour they give away free money. They get it all back in the final purchase price anyhow.

"But blackmail… never. Last night I brought along those girls just the same as I made sure the hotel had the Professor's favourite brand of whisky, that they wouldn't serve us shellfish, that I had some good cigars to offer him. Harry, this is just routine. If it had been boys instead of girls, I could organise that, too. And when you send me somebody who just wants to talk business, I'll be very happy to talk business and get to bed early. Until then…"

He sat down again. "Major Harry Maxim, takes coffee black with plenty of sugar, doesn't drink much but is particular about beer, doesn't smoke – except maybe a cigar? How'm I doing?"

Maxim smiled quickly. "Pretty well."

"And it would be girls not boys, if anything. Sheet, you should hear some of what we have to organise in the Middle East or Latin America. Europe's supposed to be easy territory."

"All it does is make you look ten years older."

"I'm sorry."

"That's okay. Sometimes you have to ask. But I'll tell you: if you're going to be baby-sitting Professor John White Tyler, you'd best get used to some help from the girls."

"Thanks."

Maxim stepped down into the frosty car-park.

Maxim, Tyler, and George clattered back to London in a helicopter; the night's excitement had startled the Army into realising that while they couldn't guarantee Tyler's life, they could at least make sure he didn't get killed while technically their guest. Maxim's wasn't the only gun on that helicopter.

Agnes drove back; she and George had come down in her car.

An MoD car rushed them from Battersea to Liverpool Street station for Tyler to catch the next Cambridge train. "All very British," George said. "Up until now you've been chairman of the review committee and thus in imminent danger of your life. But when you step on that train, you revert to being a mere academic whom nobody would wish to harm. Have you ever thought about changing clothes in a telephone box, like Superman?"

He was feeling better.

"George, I'm sure you never read those terrible American comics. And there are far more old students of mine who'd like to put a bullet in me than anybody connected with national defence." Tyler chuckled. "Anyway, thank you for your very present help, Major. I hope we'll meet again soon."

They shook hands, Tyler giving Maxim a nice open smile with his big, wide-spaced teeth. Neither of them had mentioned the lipsticked lady. Tyler climbed into a first-class carriage and George and Maxim walked away before the train left.

"Where away now?" George asked.

"Unless you want me, I'll drive out to Hayes."

"Where?"

"Army Records."

"Ah yes. Hadn't you better change first? You can't go running around dressed like a soldier or people will think you're part of a film and ask for your autograph. Shall I drop you off at your place?"

"Unless you know a good telephone box."

Maxim got home from Hayes at half past five, with the short night beginning to catch up on him. He rang George and found he needn't go into Number 10, put on a kettle and collapsed – carefully – into an old armchair.

He rented a first-floor flat in a gloomy Victorian terrace that was either in Camden Town or Primrose Hill, depending on whether you were buying or selling. He could have found a place just as cheap and far closer to Downing Street by going south, across the river. The idea had barely occurred to him. Born a north Londoner, he headed instinctively for the tribal lands between the Northern and Bakerloo lines. The house belonged to a musty arthritic widow who had taken to Maxim – as much as she took to anyone – because he was neither black nor Irish, and as an Army officer daren't bounce cheques.

"Structurally, it's about as insecure as you can get," Maxim had told George. "Somebody's just sealed off the first floor with composition board and frosted glass and a home-made door. I'll change the lock, but anyone could blow the whole thing down with a strong sneeze.

"But in practice, it might not be too bad. It's a quiet road and whenever you walk down it, there's about five old biddies sitting in their bay windows watching who goes past. I'd hate to try and mount a surveillance there. I don't know if that matters."

"It might," George had said. "Greyfriars has certainly opened a file on you by now – asssuming," he added politely, "that they didn't have one already."

The kettle boiled. He got up, made a mug of coffee and went to rout in the tea-chests in the corner. Mrs Talbot hadn't reckoned on her tenants needing much in the way of book-cases, and Maxim had only just begun to look for second-hand ones in Camden Town. Meanwhile, his books lived stacked against the wall or still in the chests. The one he wanted was, of course, at the bottom of the last chest he searched. The pages were yellowed and fragile, and the fly-leaf had the immature signature of Harold R. Maxim, but it was still this copy of The Gates of the Grave that perhaps had changed his life.

He put Duke Ellington's Far East Suite' on the record player and went back to the armchair. Later, he'd go down the road for some cans of beer. If he drank coffee for the next three hours he'd end up dancing on the ceiling.

On most afternoons there is a small, almost ceremonial, tea-party in the Private Secretaries' room. Visitors from other offices drop in and a few quiet words can often bypass a lot of paperwork and save trouble – if bypassing paperwork and saving trouble is your objective. Two days later, Maxim, Agnes and Sir Anthony Sladen were informally invited.