He was warm and he was ready. He had to set off now and keep moving, for it was so straightforward: one foot followed the other, over the bridge and back along the platform. If he kept moving, people would think he had business on the tracks, checking some complicated bit of signalling. How did his fifty-pound ticket pay for the legions of men and women who kept the industry going? There were experts, no doubt, who understood these things: they spoke the language, and he stood swaying slightly, wondering how he had spent so long on the planet knowing so little. How had he not known that the Somme was a river? For a moment he had a desire to stay alive, and read a book about the war. He could trace the whole of that sad and terrible century – not just in homage to those who had sacrificed themselves, but as a way of understanding how everyone had ended up in this place, right now. On the other hand, why be so ambitious? Why not simply learn how one particular railway line came to be, and why it connected this particular string of towns? He put the juice carton in his bag, and removed his spectacles for a final clean.

‘You’ve missed her,’ said a voice.

Michael swung round, the duster limp between his fingers.

‘What?’ he said.

‘She’s gone, I’m afraid. She doesn’t hang about.’

‘Who?’

An old man had appeared behind him – a pensioner – and Michael suddenly wondered if he was referring to some shady liaison with a prostitute. He blinked, hating himself for the absurdity of such a thought. The man blinked back at him, smelling the whisky perhaps.

‘The Proud Isabella,’ he said. ‘She came through ten or fifteen minutes ago.’

‘Through here?’

‘Yes. She didn’t stop this time, but she slowed right down. I assumed you’d come to see her. There was quite a crowd, in fact. A couple of hundred.’

The man was carrying a tablet. He flipped the cover and held it out towards Michael. Swiping from the left, he pulled up a folder which opened into a cluster of photo-files, and when he touched one in the centre it turned into the profile of a long green steam engine, with gold trimmings and a black funnel. Michael had just digested that when it was replaced by the same machine crossing a viaduct, and that changed almost at once to a close-up of its nose.

‘Beautiful,’ said Michael dutifully.

It was half past three, and he had to move.

‘You can’t account for it,’ said the man, stepping close to his side. ‘I must have seen her a dozen times, but it’s always a new experience – look at this one. I don’t know what it is – the noise, or the smell, or the… just the wonder of it. Look.’