I want you to watch this video very carefully. And then again. And then maybe once more.

Have you ever seen so much hand action in your life? To start with, there's the classic handshake-plus-arm-grab from Nick Clegg. Solid, friendly, keen. Then the handshake hardens, becomes immobile, as though they're both playing chicken -- neither willing to let go first. I bet someone had a finger crushed at this point (although neither really seems the finger-crushing type).

There follows the genial back-tap by David Cameron, a classically patronising movement. But just when we've got used to the formation, up go their arms! It's like a Siamese wave! Or synchronised swimmers! They must have practised -- that kind of perfect execution doesn't come for free -- so symmetrical, balanced, rhythmic. And both, if you look closely, wearing that same clenched smile, the one that says: "Yup. Here we are. Pretty big day. And I'm responsible and serious, and ready to run this goddam country, in case you were wondering."

Quickly, and tellingly, we're back into competition -- neither wants to bring his arm down first, like two kids in a breath-holding contest, suffering agony in order to claim victory. And then the wonderful, clinching double-back-clap-and-wave manoeuvre, so often attempted, so rarely achieved.

They really excel themselves here. Yet still that element of competition -- if you clap my back, I'll clap yours just that much harder: I am the greater statesman, and this back-clap proves it once and for all!

Who wins? Well, it's clear, isn't it? Cameron swings back in with that final back-tap, which develops, outrageously, into a back-clasp, hardly ever attempted on these shores. He hasn't let go by the time the film ends -- I imagine they're still locked in that position as they embark on their first meeting, Cameron awkwardly refusing to surrender his puppet-holding clutch on Clegg's jacket.

Who would have thought 20 seconds of film could essentially tell you all you need to know about our new government?