He jumps off the train, squeezing through the doors as they close.

'I'm very well!' he says, the train moving away behind him.

Well, that was nice of him. Now we'll have a little chat before the next one arrives, in ...

I look up at the board.

'9 Minutes.'

Nine minutes? Since when do trains take nine minutes?

Oh my God, I think. I've delayed him by nine minutes! Now I have to talk to him for nine minutes! And not just talk to him - entertain him!

I smile at Frank.

'So ...'I say, in a jaunty voice. 'How have you been?'

'Yes, very ... well,' he says, and smiles back.

I kick myself. I had only just asked him how he is, and now I've asked him how he's been. What do I ask him next? How he expects to be?

Nine minutes! For the love of God, I have to come up with nine minutes' worth of stuff! I'm not worth nine minutes! I can't sustain that level of high-octane entertainment! But I owe him! I owe Frank!

'And how is your wife?' I try.

'My wife?' he says.

'Or girlfriend!' I say.

I suddenly realise I don't know Frank very well at all. Why had I acted so excited to see him? I'd probably only met him five times before, and that was ten years ago, and now I'd inadvertently tricked him into getting off the tube to have a bad conversation.

'She's fine,' he says, but I've already forgotten what I asked him.

I steal a surreptitious glance at the board. It still says 9 Minutes. How can it still say 9 Minutes? I mask my exasperation with a smile and I think of something to say. But what can I say that lasts nine minutes? What have I got in my arsenal? And then Frank picks up the slack.

'So where are you on your way to?' he asks.

'Oh!' I say, and I'm pleased, beeause I know this. 'I'm off to buy a new printer cartridge!'

Frank's face falls a little. I search my mind for any funny anecdotes about printer cartridges, but the only ones I've got are too rude.

'Probably from Ryman's,' I say. 'Or another place. My black one has run out. I use that one the most.'

The board now says 8 Minutes. This is good. We're getting somewhere.

'Some of the colour ones run out quickly too,' I add. 'Like the pink one - but that's weird, because I never print in pink.'

I take yet another look at the board, but that's mental, because there's no way it can be 7 Minutes yet.