Driving along the middle lane of the motorway at 80mph, somebody following behind you as you overtake a load of cars in the inside lane. The traffic on the inside disappears, you have an empty road in front of you, and your mind flashes back to your driving lessons decades earlier, the highway code, and the rule that once you've overtaken someone you should move over into the inside lane. You weigh it up briefly for a few seconds, what's in it for me you ask, only hassle can come from it you reason, but I'm not going to hog the middle lane so I'll move over.

You do your good deed, but as soon as you've pulled in you catch a glimpse of the man behind you nodding his head in excitement, the thrill of his year playing out before him as he launches into a five minute attempt to overtake you at 80.1mph in his groaning 1.0 litre Vauxhall Corsa. You end up getting stuck behind a truck and have to hit your brakes to let him past while he sails off into the distance hogging the middle lane like a limpet.