Why does everybody else drive on the wrong side of the road?

It is only a couple of weeks until I head out to France and then Andorra. I am almost looking forward to the drive this year. For one thing, going to the Alps first means I can avoid Paris which is my least favourite part of France for driving. Mainly though it is the fact that once out of England, queues on the motorways become a rarity.

I get used to driving on the other side more easily recently, but I still wonder why most of the world drives on the right hand side. There are good reasons for driving on the left, such as it being easier for a right handed swordsman to mount a horse on the left hand side without the sword getting caught on the animal's back. More relevantly you could argue that driving on the left means keeping the right hand on the wheel while changing gear (or even changing the CD).

Until around two hundred years ago, people in most countries rode their horses and drove their carriages on the left. Then France switched to the right, along with all the countries ruled by the French at the time. Eventually most of the world followed suit. There are various theories about why the French switched. There is the idea that the common people (without horses or carriages) always walked on the left (to avoid being run over) and after the revolution nobody wanted to look like a member of the aristocracy so everyone travelled on the left. Or there is the theory that it was to spite the English, and I have also read a complicated argument about the differing ways French and English coaches were driven. My favourite theory though is the story that Napoleon was left-handed, and therefore preferred to mount his horse from the left. As a lefty myself I like the idea that a single bloody-minded left-hander could have forced almost the whole world to do something the left-handed way. Even better, the world is still doing it the left handed way two centuries later.