It was an occupational hazard. A risk they’d lived with for so long that many of them believed it would never happen. Yes, it was well known that a pod had been blown up once at St Mary’s, but they were morons there and the only surprise was that it didn’t happen every day. That explosion had almost completely demolished the structure in which the pod had been standing. The damage caused had been extensive and widespread and that had been in an underpopulated rural area. Here, the potential for catastrophe was massive. Because this was central London. And most of the Pod Bay stretched far under the Thames.

There was an established procedure. Drills were held monthly. The procedure was rigorous and unchangeable. You had thirty seconds to exit the building by whatever means seemed good at the time. After that, the blast doors would come down on every floor and all chances of escape would be lost. After thirty seconds, people were no longer important. Damage control was the main aim. The blast doors would come down – for all the good they would do – and anyone still in the building would soon find themselves buried underneath most of it. Which was the easy way to go.

Because there might not be an explosion. If the pod simply sat there, haemorrhaging radiation, then any survivors would spend their last few seconds hammering uselessly on the blast doors demanding to be let out and then, within a horrifyingly short time, succumb to weakness and fainting. Their gums would bleed and soon – very soon – their teeth would fall out. And their hair. Their skin would start to blister, split and then slough off completely. They would be consumed by raging fevers, bloody and involuntary diarrhoea, and massive vomiting. At that point it was generally reckoned that death wouldn’t seem so bad after all.

Jane barely had time to jump out of her skin at the noise before the door crashed open and two radiation-suited figures burst in, shouting, ‘Get out. Get out. Immediate evacuation. Get out now.’

Varma headed for the door. Her scratchpad fell, unheeded, to the floor.

‘Lead the way,’ shouted the one on the right. ‘You know the designated exits?’

‘I do. Follow me.’

The corridors were choked with people trying to get to the lifts. The detention area was underground – along with the Pod Bay. They were at ground zero. The furthest point from safety.

The same thought was in everyone else’s minds. There wasn’t panic – they were the Time Police, after all, and they remembered their drills. Marshals and evacuation officers held doors open and ushered people in the right direction. Everyone moved at a fast trot, conscious of the seconds ticking away.

Each of Jane’s arms was tightly held by the evacuation officers. There was no chance of escape. They followed Varma down the corridor at a running walk.

‘This way,’ she shouted. ‘Exit C3.’

She turned right.