He knew straight away.

He was returning from a walk with his wife when he heard it. He looked up to see it passing overhead.

It was heading west.

Years of experience kicked in. Numbers. Probabilities. Knowns and unknowns. The scientist couldn’t be certain. But he knew that what he had seen was probably about 20 megatonnes. It was probably Russian. It was heading towards Birmingham. They would be in the blast radius.

His brain had already worked out much of what would happen and how soon it would happen. The rocket scientist didn’t know what to tell his wife. He turned to look at her, she was looking closely at his face.

“So it’s begun,” she said.