‘Any time now, should be.’ As Gareth spoke one of the screen-watchers called the supervisor over. She said something to the others, who switched their monitors to one of the rear approaches to the building, a gravelled track that led to high locked gates on the far side of the park bordering a public lane and a wood. Two men were climbing the gates. Charles and Gareth moved farther into the room to get a better view of the screens.

Then came the sound of smashing glass, followed by a shout from the security guard by the cubicles in the entrance hall and then two shots in rapid succession, very loud. Everyone in the control room turned away from the screens to look. The security guard was spreadeagled on the floor and a man wearing a grey suit and carrying a pistol was pressing buttons on the entrance control desk. Another man wearing a raincoat and carrying a sledgehammer ran towards the screened-off office where visitors’ passes were issued, raising his hammer. The woman behind the screen tried to get off her chair but slipped beneath the counter onto the floor a second before the man swung his sledgehammer with both hands at the glass door to the side of her office, smashing it. Some control room staff got up from their desks, others sat staring. The supervisor ran to her own desk and pressed the alarm, a harsh jangling that rang throughout the building. Outside, two Land Rovers accelerated abreast of each other from the car park towards the broad steps leading up to the entrance. They slowed as they reached the steps but continued up them, jolting and bouncing, then accelerated again across the terrace and into the entrance. A number of black-clad, hooded men carrying sub-machine guns jumped out of each and ran in through the glass cubicles, which were all now open.

Charles and Gareth flattened themselves against the wall as the control room staff disintegrated in panic. The supervisor shouted into the microphone on her desk, ‘There is an incident in the building. Stay where you are! All staff stay where you are!’ Before she had finished one of her team, a man, shouted into another microphone, ‘Building under attack! Intruders in the building! Evacuate the building! Evacuate now!’ Several of the staff ran out of the control room onto the balcony, where they stopped as if suddenly frozen as the intruders split into two groups and ran up the curving stairs on either side. A couple of the control room staff stayed at their desks looking to the supervisor, who was shouting ‘They must stay where they are!’ at the man with the other microphone, who, oblivious to her, was shouting into it again, ‘Do not use the lifts! Lifts not working! Evacuate! Evacuate!’ There were more shots.