Chapman scrutinised the screens, then tapped one. ‘That’s one of our programme sellers.’ Fielding went over and peered at the screen. A small crowd had gathered around a man lying on the ground. Three men in fluorescent jackets were trying to get them to move back while another steward was kneeling next to the injured man.

‘I’m not sure where the other one is,’ said Chapman.

‘Okay, I’m going to have to tell the Met Control Centre,’ said Fielding, reaching for the radio. ‘But, frankly, I’m not sure what to tell them. Do we have one nutter with a knife or is something bigger going on?’

Chapman shrugged. He had no idea.

Fielding was just about to radio Superintendent Enfield, but the superintendent beat him to it. ‘Andrew, we might have a problem there.’

‘Yes, sir, I was just going to call you. We have a number of casualties here and we’re not sure what’s going on.’

‘Casualties?’

‘Two people with what appear to be stab wounds. No suspects but with severe injuries.’

‘Is it possible they are gunshot wounds?’

‘Gunshot wounds? I don’t think so. We haven’t heard shots and everyone who enters the stadium is searched.’

‘We’ve had reports of a possible sniper in one of the blocks overlooking the stadium.’

‘A sniper?’

‘That’s what I’m told. Is it possible the wounds are sniper-related?’

Fielding waved to get Chapman’s attention. ‘Could the woundings be gunshots?’

Chapman shook his head. ‘No one’s reported hearing shots.’

‘There might be a sniper.’

‘It’s possible, I suppose.’ He scratched his head. ‘But why?’

‘We’ll check and get back to you, sir,’ said Fielding, into his radio. ‘In the meantime, do we evacuate?’

‘What’s the state of play there?’

‘Round two is just about to start.’

‘Do you think you could evacuate, if necessary?’

‘We could try, sir, but I’m not sure we’d be listened to.’

‘I’ll get back to you,’ said the superintendent.

The man stepped through the metal detector, hesitated, then walked over to the table to pick up his keys and mobile phone. He turned to wait for his friend, who came through the metal detector grinning. It must have beeped because a security guard stepped forward and began to pat him down.

Mohammed al-Hussain took aim at the man being searched, the security guard, then across to the man at the table. He aimed, took a breath, let half of it out, and squeezed the trigger. Half a mile away, the man fell to the ground in agony.

It was only then that he realised there was a helicopter outside the building, off to the left. Amma al-Kawthari was at the window, staring at it. The helicopter was several hundred yards away but the nose was pointing in their direction. ‘They’re going to shoot us!’ he said.

Al-Hussain smiled. ‘It is a police helicopter and they are not armed,’ he said. ‘But even if they were, they would not be allowed to shoot us. In England the police cannot attack civilians. That is the law.’