THE COFFEE-WAVE

I'm in Starbucks and an extraordinary phenomenon is taking place.

Every hour or so, the queue stretches out of the door and the tables are packed. Then, some half an hour later, there's nobody here.

It's almost like a wave, peaking in amplitude and then dipping to zero at a fixed frequency of 1/60 cycles per minute.

What causes this coffee-wave? What generates it? Where do these people come from? Who are they?

Well, there's the grumpy teenager on her phone next to her grandma; there's the dishevelled couple talking about money. There's the single Mum whose favourite and least favourite word is apparently 'shush' - it isn't working. There's the young couple eating toast, and the even younger couple who seem to be unable to remain out of physical contact with each other.

There's the tattooed man busily scratching a lottery card with a two-pence piece and there's the well-spoken coiffured lady who's just ordered a 'hot babycino' and a 'cold babycino' at the same time. She seems to be alone; presumably she's conducting a science experiment.

Then there's the older lady with a sad  expression, a walking stick and a bunch of flowers. A burly man in an England tracksuit top has pulled up a chair next to her with two slurping mugs.

"How much did that cost?" she asked.

And then there's the queue, the snaking chain of arrivals to the coffee-wave: a row of gold-clasped handbags slung over the shoulders of exasperated-looking women with sunglasses pushed up over their pinned, shiny hair. A tall man in glasses peers into the gleaming cabinet of cakes and pastries in the same way I imagine a meerkat examines an anthill.

A pretty girl with long blonde hair taps her fingers at a table alone, waiting to be joined so that she can pretend not to look at her phone. Meanwhile, the baristas rush around with green aprons and tongs shouting things like 'cappuccino?' and 'grande latte?' over the sound of the swooshing coffee machine behind them.

This is the coffee-wave. In a few minutes, the tables will be clear and the green aprons will be wiping them with ineffective cloths, grabbing the remains of lattes and americanos between their fingers and carrying the detritus to the bin, waiting for the next peak.

I wonder whether people work on thirty-minute cycles with this kind of thing. Perhaps we accidentally synchronise? Perhaps thirty minutes is the optimum time for purchasing coffee, finding a table, having a chat and then going off to do the next thing?

Clearly not me then. For one thing, I'm drinking tea. And for another, I've been here long enough to observe two cycles of the coffee-wave.