"I'm sorry." He smiled at the guard and went on down the corridor.

The entrance hall was deserted, the front door slightly open. Then a uniformed policeman leaned in from the hats-and-coats lobby and said in a hoarse whisper: "Get back sir. There's a grenade in there."

Why on earth do people always whisper in the presence of explosives?

"Where?" Maxim asked.

The policeman pointed to Chippendale's huge black leather hooded chair. An olive green egg the size of a fist had rolled up on the tiles beside it. Maxim squatted down and peered at it.

"Sir" the policeman squawked in what was still really a whisper. Maxim bowed down to the grenade. Telling the story afterwards, most people said he was listening to it. In fact he was smelling it. Then he got up and walked across to the lobby.

The policeman had a phone in one hand: several of the messengers were peering out from behind the rack of visitors' coats.

"You can cancel the bomb boys," Maxim said. "It's a drill. A dummy." The policeman just stared at him. Maxim went back and met George coming down the corridor, very much more likely to blow up than any grenade.

"Harry, what the hell did I just tell you? You aren't the bloody-"

"It's a dud, a drill. But if you want a nice big news story, let the Ordnance come screaming round and put mattresses on it."

The PM was out of town again, so the story lacked something already. Maybe it could be played down as just a bit of hooliganism, whatever it really was…

"How can you be sure?"

"Oh balls," Maxim said, and went back and picked up the grenade and held it under George's nose. "Smell it. There's no fuse been burning. Just fresh paint. You don't paint a grenade before you throw it. But the drill comes in light blue; somebody's tried to make this look live."

George pushed the grenade gently away. "Harry, if that thing were now to explode. I would never forgive you." He went to find the Security Officer. Maxim walked back upstairs.

George rang him just after lunch. "You are the hero of the hour. You, with your own hands, nay, your own bare teeth, personally defused several time bombs within split seconds of doom and destruction… you haven't heard any of these rumours? Never mind, in Number 10 the hero of the hour lasts just that long. They've got the chap that did it over at the Cannon Row fuzzery and I think we ought to have a word."

"Is it all right with the police?"

"That's fine, all squared away. I'll see you downstairs in five minutes."

On the way out they passed the Security Officer. He had disliked Maxim from the very beginning; now he gave him a smile of pure hatred.

Just across Whitehall and down a side street, the police station was a shapeless grimy-black Victorian mass in the shadow of the old Scotland Yard building. They sat in the Chief Inspector's office while a sergeant took Maxim's finger-prints, since he'd handled the grenade without due care and attention.

"Our friend's name is Charles Farthing," the Chief Inspector read from his notes. "Aged fifty-one, unemployed, there's an address in Barnes that we're having checked out. He's either divorced or getting divorced, but he didn't want to say much about that,"

"Did he put up a fight?" George asked.

The Chief had a skull face with curly grey hair and pale blue eyes. He obviously knew George well, but still took a cautious time before answering. "No, he came quite quietly, as I understand it. He just threw the… the object in through the front door, and I believe he shouted 'Grenade!' or something along those lines. Then he let himself be arrested by the constable on duty at the door."

He had, it seemed or was alleged or was held, got the door opened by saying he wanted to present a petition against some motorway scheme.

"Has he been charged?" George asked.

"Only with creating a disturbance. We're holding him so that a doctor can have a look at him, but I wouldn't say he was drunk."

"Has he asked for a lawyer?"

"No, sir. He seems just to want to get into court and say his piece."

"About what?"

"That's why I called you, sir."

George stared at his fingernails. "Is it all right if Harry here goes and has a word with him?"

"It's perfectly all right with us, sir, although the accused doesn't have to answer." He gave Maxim a warning look.

At the far end of the narrow cells corridor there was a deep washbasin where Maxim got most of the fingerprint ink off. Only one of the cell doors was shut, and on the little blackboard fixed to it was chalked FARTHING DISTURB "Just so that we don't get them mixed up when the van comes for them in the morning," the Chief explained. Maxim thought of saying they'd missed out a do not, but neither the dim corridor nor the occasion encouraged jokes.

A uniformed policeman peered in through the Judas window, then unlocked the door. It shut behind Maxim with the whirr and snap of an automatic lock.

The cell looked as if it should smell, but it didn't. It was long and high, lined to head height in glazed white brick and with a wide wooden shelf running right down one side. At the near end it was a bed, at the far end it became a lavatory seat. But there was no cistern or chain, from which you might hang yourself. You pressed a buzzer and sooner or later somebody came and pulled a chain in the corridor. Even the single light bulb was actually in the corridor, shining in through a thick porthole, so that you couldn't electrocute yourself or slash your wrists either.

In the gloomy light, Charles Farthing sat on the mattress puffing quickly at a cigarette. He didn't look up. Maxim walked past him and sat further down the bench.

After a time, he said: "Nice place you've got here."

"I don't come here often." The voice shook a little. He had a puffy face with sunken eyes, a big nose and thin dry hair. He wore a suit that was some years out of date and greasy suede shoes – though perhaps you didn't put on your best clothes to get arrested in.

"And who are you?" Farthing asked.

"Harry Maxim. From the Ministry of Defence."

"Oh yes." Farthing threw his cigarette against the wall and sparks spattered in the dimness. "The dear old Mine of Dung. They're all honourable men, there. So they sent you down here to shut me up, have they? Well, you can go and tell that I'm going to let it all hang out, as the Americans put it so charmingly. All, everything." His voice had a flatness within the anger, as if a regional accent had been carefully polished out.

"All what?"

"I'll tell the court, don't you worry. They can't stop you there."

"They don't let you make irrelevant speeches, either."

For a while neither of them said anything, then Maxim asked politely: "What work do you do?"

"I don't do any, do I? I was twenty years in the arms business, until you people started buying everything from Washington or the Germans. Do you know what we were doing at Warrington before I was made redundant? Sub-contract work on grenades – and even those were really the Yank M26."

So at least we know where the drill grenade had come from.

"And you wait and see with these anti-tank mortar trials."

Farthing went on. "It'll be the same again there. You wait and see."

"Is that what you're going to say?"

"It gets worse than that, doesn't it?" Farthing looked craftily sideways.

"I've never known it when people weren't saying the country's defences were going to the dogs."

"Yes, but you people weren't always killing people and suppressing evidence to hush it up, were you?"

"Who got killed?"

"You know bloody well who!"

"Sorry, I'm new in Whitehall."

Farthing's look turned to distrust. Then he lit another cigarette, using both hands to keep the match steady. "Most people think the government makes the decisions, don't they? Or you people. But governments come and go – even you people get transferred every now and then. And you can have three different prime ministers in the time it takes to develop a new tank or field gun. But there's one man who's always there, one man who makes the real decisions and he's not the right man to do it. He'll see us all destroyed, ruined. And I'm going to say it, to tell them. Even if it gets me killed, too." He ended on an almost triumphant note.