‘You’ve no idea where it came from?’ the officer asked, and O’Reilly shook his head.

‘It looks new,’ said O’Reilly. ‘I thought of keeping it but my wife said no, it might belong to someone, and besides, you know, there might be a reward or something. So she said take it to the police, you know, and so here I am.’ O’Reilly smiled like an idiot. He was wearing horn-rimmed glasses with thick lenses, a flat cap and a sheepskin jacket. That was all the disguise he needed because even if they ever connected the delivery of the video recorder with the explosion, all the guy would remember would be the hat and the glasses. People’s memories were generally lousy when it came to describing faces, even with the latest computerised photofit systems.

‘Very public-spirited of you, sir,’ said the policeman. ‘Now, can you give me your name and address?’

O’Reilly gave him a false name and an address in nearby Battersea and explained again how he’d found the video recorder while the policeman carefully wrote it all down.

‘Right, sir, that’s all. We’ll be in touch if it isn’t claimed,’ he said, and O’Reilly thanked him and left. He passed the housewife outside, kneeling by her child and wiping its face with a paper handkerchief. She looked up at him and smiled and he winked at her. ‘Lovely kid,’ he said.

The policeman lifted the box, grunting as he did so, and carried it out of the office and down a white-tiled corridor to a windowless storage room. He found a space for it on one of the grey metal shelves, next to a set of fly-fishing tackle and a bundle of umbrellas. The room was full of abandoned or forgotten belongings, all waiting to be taken to one of the city’s lost property storage centres. The policeman walked back to the reception desk and forgot all about the video recorder and the man who’d delivered it.

The bomb was similar in design to the one they’d used outside the Knightsbridge department store. The Bombmaker had stripped out most of the workings of the video recorder and replaced it with twenty pounds of Semtex explosive. There were no nuts and bolts in this bomb because the aim was to demolish a building rather than mutilate crowds of people but it used a similar detonator and timer. There were two anti-handling devices, though, just in case it didn’t go off for any reason. Any attempt to open the casing would set it off, and it was also primed to explode if it was connected to the mains, just in case any light-fingered copper decided to pop it into his car and take it home. The Bombmaker did not have a very high opinion of the police, be they in Belfast or London.

O’Reilly delivered the bomb at four o’clock and it was set to explode an hour later, just as the shifts were changing at the station. He was back in the Wapping flat well before the timer clicked on and completed the circuit which detonated the bomb in a flash of light. The force of the explosion blew out the front and the back walls of the police station and the two floors above it collapsed down, trapping and killing dozens of men and women in an avalanche of masonry and timber and choking dust.