All white, smooth operators

Not that it's a beautiful work of art, or anything (instead of water lilies, we have damp copies of the Metro trodden into the pavement).

But it is like a Monet painting in that, up close, it is blurry and only people standing at a distance have any real idea what's going on.

A few weeks ago, my mother phoned me. "Have you had a flat white?" she demanded.

"Pardon? A what?" "A flat white. Apparently, they're all the rage."

I mentally scan through a few speculative options.

Have I had a flat white? It sounds like a shark.

Is it a shark? Are we all meant to be eating shark burgers in gastropubs now?

Have wild boar sausages finally had their day?

Or maybe it's an activity, flat whiting.

Like free running or pilates or something, that involves lying still on the floor under a silk sheet as a cure for cellulite?

Maybe it's a flat, white person? Surely she can't mean a flat, white PERSON?

"It's a coffee," she says, when it becomes clear that I am not the Suzy Society I profess to be. "Everyone in London's supposed to be drinking them. It said so on Radio 2."

"Oh. Really?" "In London, where you live." "Yes, Mum." "Well? Have you had one?" "Ummmmm. No. Not to my knowledge. I thought we were still excited over the Macchiato."

So, this got me slightly worried.

Am I losing my grasp on the fleeting world of popular culture in the capital?

When did I miss this sudden development?

Was it those two days I spent watching Crystal Maze on Challenge?

While I was with Richard O'Brien in the sunken ship, was everybody else out in coffee houses, comparing foaming techniques and laughing gaily as they tipped lattes in the Thames? WHY WASN'T IT ON THE NEWS?

After a little further research, however, it transpires that nobody I ask has heard of a flat white.

I conclude that it must be one of those provincial myths about London-dwellers, like "we get mugged on average once a week" or "Boris Johnson makes us laugh out loud", or "you're never more than three feet away from a heroin addict".