When the roads go metric the speed limit on motorways will be 120km per hour.

What’s that in old money, then?

Er, hang on, um, let’s see. Multiply by .6214 — no that’s much too hard. So, OK, divide by eight and multiply by five . . .

Good Lord, you can’t be doing all that counting on your fingers and frowning stuff while you’re driving.

It’s 74.568 miles an hour.

Swizz! That’s not much more than we’re allowed now.

Yes, but it works out better in town — it’ll be 50km/h. That’s 31.07mph. It’ll shave seconds off the school run.

Better chance of mowing down old ladies in the SUV while talking on your mobile, then.

Wonder how the police will deal with it: “Excuse me, madam, but did you know you were exceeding the speed limit just now?” “Oh really? And by how much, officer?”

“Six kilometres an hour, madam.”

“Six? Really? And how much would that be in miles and yards and feet, officer? I’d like a precise answer, please.”

The London Marathon will be nearly 39km. Makes you tired to think about it. What will the Royal Mile be? The Royal 1.6km?

You know, we’re the only country in Europe that doesn’t have metric distance signs. Neil Kinnock (remember him? ginger, Welsh bloke) says that imperial road signs contradict our image as a modern, multicultural, dynamic country where the future is approached with creativity and confidence.

UKIP won’t like it. They’ll be spray-painting metric signs and standing on motorway bridges in Spiderman suits.

That’s Fathers for Justice.

Well, same sort of thing.