‘They do it because it’s easier, and it gets their detection rates up,’ said Matt. ‘A motorist who goes a few miles an hour over the speed limit is a nice soft target. Not to mention all those cases where people tackle yobs causing trouble. If they don’t get beaten up by the yobs –’

‘Or killed,’ said Claire.

‘Yes, or killed,’ agreed Matt, ‘then they get arrested themselves. And yet at the same time you hear stories of police officers standing around doing risk assessments while someone is dying. It’s ludicrous. I can tell you, Dad would never have done that. He would never have hung back if he thought he might save someone’s life.’

‘No.’ Claire was quiet for a moment. ‘I suppose you hear this all the time, Ben.’

‘Pretty much.’

When it had come time to leave the arboretum, Claire insisted on taking a photograph of her two brothers on her digital camera. She posed them near the rain-streaked windows to get the best light, gesturing them to get closer together until their shoulders were touching. Ben tried to smile, but could sense that his brother was as stiff as he was. Not the best family portrait, probably. But Claire didn’t seem to notice, flashing off a few shots before pulling up her hood and leading them out into the rain.

‘All right,’ Matt said. ‘I suppose it’s just today, visiting this place. Thinking about Dad. About how much things have changed in those few years. He would never have been able to live with it.’

‘I know,’ said Ben. ‘I know.’

Ben found he could listen to their comments without even being tempted to argue. There was nothing in them that he hadn’t heard before. Yes, it was hurtful that his own family should have these views, but he wasn’t surprised by them. Matt read the Daily Mail and the Daily Telegraph, after all. Stories like these were commonplace. There was some new incident in the media every week. A view of the police as the enemy was spreading rapidly among ordinary members of the public. Like a disease, it passed from one person to another by word of mouth.

And this wasn’t the way it had been meant to be. Not in this country, anyway. In Britain, there was supposed to be policing by consent, a partnership between the police and the public. It was never imagined that police officers would be attacked on the street by members of the public just because they happened to be there.

Though it upset him to hear what was said, it was difficult for Ben to summon the enthusiasm to put up any defence. He heard much the same concerns at work day after day, from the people caught in the middle of the trap.

And the worst thing of all was that Matt had been right. Sergeant Joe Cooper would never have stood by while someone was dying. He would have torn up the risk assessment forms and thrown them in the face of anyone who tried to stop him.