How do you know what time it is? Look at your watch, suggests Gail, practical as ever.

Undeterred, Fred presses on. We all know that the Earth spins around its axis, and hence it’s split into time zones which run North-South. That way, wherever you are on the planet, it’s ‘noon’ for you roughly when the sun’s at its highest point.

Unless, that is, you’re near the poles, where all the time zones meet. What then?

Suppose this mark on the floor of the How studio is the South pole. All the time zones meets there, as you can see.

But that presents a problem – every step you take moves you around several time zones. You could walk round and round in little circles, going backwards and forwards in time.

So if you’re on an expedition to the South Pole, how do you know what the time is? It seems that time is meaningless.

Perhaps note. Suppose you’re in regular contact with people in a more conventional time zone – perhaps you’re a British expedition, talking to the British Antarctic Survey back in Cambridge.

Well, the simplest thing to do would be to set your clocks to the time back in Cambridge. It really doesn’t matter to you, so you might as well fit in with the folks back home. On the other hand, a French expedition:

They’d do well to set their clocks to the same time zone as Paris - European time, one hour ahead of Greenwich Mean Time.

Now, American expeditions to the Antarctic tend to set sail from Christchurch in New Zealand, so the Americans use New Zealand time, twelve hours ahead of Greenwich.

So there you go – if you’re heading to Antarctica, you just leave your watch set how it was. Simple. That wasn’t so bad, was it, Fred?