Inside the box were two batteries, a black plastic alarm clock with a digital display, a small aluminium tube, a tangle of different coloured wires and five pounds of pale-brown Semtex explosive in which was embedded a detonator. As the roadsweeper unclipped his shovel and carefully swept up a cigarette packet and a pile of dust, the clock began ticking off the seconds. The man was in no hurry. The clock was set for five minutes, but even when the time was up the bomb would not explode. The clock merely completed the circuit for the second switch, a mercury tilt-switch which acted as a motion sensor. The design prevented the device going off accidentally. It was one of The Bombmaker’s favourite bombs, and one of the simplest. There were no booby traps because it was a small bomb and if it was discovered the bomb disposal experts would dump it into an armoured chest and take it away rather than try to deal with it on the spot.

The streetsweeper left the mews just as the five minutes were up. He left his cart a quarter of a mile away, along with the hat, the donkey jacket and the gloves. Fisher had planned everything down to the last detail. O’Reilly kept on walking until he saw a black cab. He hailed it and took it to Victoria Station where he waited for half an hour before catching another cab back to Wapping.

The front door of the mews cottage in Chelsea opened at the same time as the cab turned into Wapping High Street.

Erica’s hair still looked as if she had just got out of bed, but this time her lipstick had gone and as Jephcott kissed her he smelt her sex rather than her perfume. Her classy clothes had gone, too, and in their place she wore a white silk dressing-gown. Something else that he’d bought for her.

‘Tomorrow?’ she breathed, her body tight against his.

‘No, my love, I’m afraid not,’ Jephcott replied. ‘I’ll call you.’ Over her shoulder he looked at his watch. Plenty of time. He kissed her again and then pulled himself away. She closed the door behind him with a final goodbye, and he adjusted his tie as he went to the car. He unlocked the door to the Rover and got in. He looked at himself in the driving mirror and smoothed down his hair before using the breath-freshener again. The Rover started first time and as he edged it forward the bomb went off, blasting through the wheel-arch and taking off both of his legs in a burst of fire and exploding metal.

Detective Chief Inspector Richard Bromley was filling his briar pipe from a weathered leather pouch when the phone on his desk rang.

‘It’s the front desk, sir. He’s here again.’

Bromley groaned. ‘Tell him I’m busy.’

‘I’ve done that, sir. He says he’ll wait.’

‘Tell him I’ll call him when there’s any news.’

‘I’ve done that, sir.’