Many years ago now I picked up a colleague (the boss's son, actually) to drive down to London from Glasgow to collect some equipment.

First thing he did was slap a massive TomTom sat nav in the middle of the screen. He got pretty indignant when I told him to take it off, because it was blocking my view out the windscreen.

"But how will you know where to go?"

Dude, it's London. London is south. We go south. We go south for like eight hours.

We can use the sat nav for the last dozen or so of the 400-odd miles we'll be driving.