The sniper rolled onto his back and swung his rifle around. Shepherd dropped into a crouch and pulled the trigger at the same moment as the sniper pulled his. The two cracks overlapped and Shepherd saw his round smack into the sniper’s chest as the sniper’s bullet whizzed past his neck. Shepherd fired again and the second shot hit the man two inches below the first. The sniper fell back and the rifle clattered onto the table.

There was a dull thud behind Shepherd. He looked over his shoulder. The sniper’s round had hit Walker in the face and he had died instantly.

Graves and Leigh dragged the Asians off the sofa and threw them to the floor, face down. Leigh had his foot in the small of Assadi’s back and was screaming at him to lie still.

‘Get the gates open! Let the ambulances in! We’ve got casualties here!’ shouted the security guard. He waved at the two men on the gate and they followed his instructions. Outside there were two ambulances, lights flashing and sirens wailing. ‘Tell them to cut the sirens!’ shouted the guard. He put his transceiver to his mouth and spoke to Ian Chapman in the control centre. ‘The ambulances are here, sir.’

‘Get them in as quickly as possible,’ said Chapman. ‘The casualties need to be on the way to hospital immediately.’

As the gates opened, both ambulances cut their sirens and lights, as if the drivers had read the security guard’s mind. They drove through and he pointed to where they were to go. Two more ambulances were heading down the road towards the stadium, sirens wailing.

‘Clear!’ shouted Shepherd, and Willoughby-Brown peered cautiously into the room. He grimaced when he saw Walker’s body on the floor. Leigh and the other armed cop had bound the wrists of their prisoners and were staring stony-faced at their dead colleague.

Willoughby-Brown went over to the cops. ‘Back-up’s on the way, so you two can stand down as soon as they’re here.’

Leigh shook his head fiercely. ‘We’re booking them,’ he said.

‘No problem,’ said Willoughby-Brown. ‘I’m sorry about Neil.’

He went over to look at the sniper. ‘The old one-two,’ Willoughby-Brown said, when he saw the two wounds in the man’s chest. ‘Does the job every time.’

Shepherd joined him. ‘I’ve seen him before,’ he said quietly.

‘One of Yilmaz’s passports?’

‘No. He was the sniper in Syria when we took out those two British jihadists. The one who ran before the missile hit.’

‘Seriously? He’s a long way from home.’

‘They all are,’ said Shepherd, picking up the weapon.

‘What sort of gun is it?’ asked Willoughby-Brown.

‘It’s a rifle, Jeremy.’

Willoughby-Brown flashed him a cold smile. ‘I realise that. What is it? American?’