As if the world turns to slow motion again, I see him glance at his phone once more and then go to pocket it, but instead of pushing it into the pocket of his jeans, it slides straight past and lands on the carriage floor at the exact moment the doors open and he, along with everyone else, rushes through them.

He hasn’t noticed.

Without thinking, I dart forward and grab the phone from the floor before someone treads on it. I stare at it for a moment. This is his phone and I have it. He doesn’t know he dropped it. There’s still time to catch up with him and give it back.

Zinnia will probably kill me for being late for work, and I’m still a few stops away from where I usually get off, but I don’t have time to wait. I follow the swarm as seemingly every other person in our carriage floods out, and I pause in the middle of them, aware of the annoyed grunts of people pushing past me as I try to see where he is. I follow the crowd off the platform and up the steps, straining to see over people’s heads and between shoulders.

I’m sure I see his hair in the distance as the crowd starts to thin out, but he’s moving faster than a jet-powered Usain Bolt after an energy drink.

‘Hey!’ I shout. ‘Wait up!’

He doesn’t react. He wouldn’t know who I was calling to, if the guy I’m following is even him.

‘Hey! You dropped your—’

Another passenger glares at me for shouting in his ear and I stop myself. I’m already out of breath and Train Man is nothing more than a blur in the distance. I rush in the same direction, but those steps have knackered me, and the faraway blob that might still be the back of his head turns a corner under the sign towards the overground trains, and I lose sight of him.

I race … well, limp … to the corner where I saw him turn, but the station fans out into an array of escalators and glowing signs and ticket booths, and it’s thronging with people. I walk around for a few minutes, looking for any hint of him, but he’s nowhere to be seen. In the many minutes it’s taken me to half-jog half-stumble from one end of the station to the other, he could be on another train halfway across London by now.

I pull my own phone out and glance at the time. I’m twenty minutes late for work, and still three tube stops and a ten-minute walk away. Zinnia is going to love me this morning. I put my phone back in my pocket and slide his in alongside it.

I’ll have to find another way to get it back to him.