I return to my corner, to find Colin looking bemused.

'What's Lee Mead doing here?' he says.

I cast my eye to the bar. Lee Mead is there, sipping champagne. I have never met Lee Mead before in my life.

I hug Colin.

'What are you doing?' he says, horrified.

I shrug, and pick up a chip.

THE SNIFF

Sometimes, as I am walking home at night, I have noticed that any man walking in the opposite direction to me will sniff slightly as they pass. Or they'll cough. Or they'll wipe their mouth with the back of their hand. Since I've started to notice it, I've started to notice it every time I pass a fellow man. It has become a little disconcerting.

'Watch this,' I'll say to a friend, in the dying light of a summer night. 'This man will sniff or cough just as he walks past us.'

And then the man will sniff or cough just as he walks past us, and I will win a pound.

Now, I'm pretty sure this can't be happening just to me. This cannot simply be an elaborate way for me to win one pound every time I leave the house. If it is, I'm not sure who arranged it or what they're getting out of it, but they must be operating on a loss.

So it's definitely something else. But what?

'It's evolution!' says Colin, with wild, excited eyes. 'Don't you see? It's evolution! Do they look at you while they sniff at you?'

'They don't sniff at me,' I say. 'They just sniff. While averting their eyes.'

'And do you hear them sniffing before you pass? Do you hear them sniffing afterwards?'

'No - it's always exactly as we pass.'

'Do you ever sniff?'

I think about it. I suppose I do sometimes. But mainly I pat my pockets or look at my watch.

Hey - why do I pat my pockets or look at my watch?

'You're an animal, Dan,' says Colin. 'You're behaving just as a monkey would!'

'What do you mean?'

'You have identified some kind of primal reaction. You must have!'

I feel momentarily proud of myself. Colin thinks I must have identified some kind of primal reaction!

Wait. What?

'The men that are passing you at night do not know you. But they do not want to show weakness in front of a stranger. They need to remain strong and indifferent in the face of any potential threat.'

I think about what Colin is saying. And then my brain starts to hurt and so I ask him to say it again.

'They want you to know they're not afraid of you, Dan, and they also want you to know they mean you no harm.'

'So they sniff?'