That fellow Napoleon has an awful lot to answer for. Not satisfied with conquering the whole of Europe he has left a legacy that divides us from the Continent and indeed from most of the world.
In Ireland, influenced of course by Britain, the convention is to drive on the left hand side of the road. That puts us in a minority that may seem as if we're at odds with the world but I can tell you on good authority that everybody's out of step except us.
The authority is his late Holiness Pope Boniface the Eighth, who in 1300 AD issued a proclamation decreeing that all pilgrims on the roads to Rome should pass each other 'right-side to right-side' - in other words drive on the left. This eventually became the universal convention.
The troublesome Mr. Bonaparte, in establishing an empire that stretched from Lisbon to Moscow, ordered his troops to march on the right in defiance of Rome. That Napoleonic convention has lasted to this day.
The USA, in its infancy, adopted the Napoleonic system. It had the merit of meaning that when two right-handed drivers passed each other on the right they stayed out of the range of each other's whips. But it was also a way of thumbing their nose at John Bull.
In the modern world these once arbitrary decisions have added billions of euros to the cost of making cars. Every vehicle has to have two production lines; one for right hand drive and one for left.
As a general rule, with exceptions like the US, anywhere that used to be governed by Britain drives on the left. The formerly-British countries of Australia, New Zealand and India are significant examples; there are also large parts of the Carribbean and of southern Africa and European examples like Cyprus and Malta.
Japan was never under British rule of course but they independently evolved the ‘stay left’ convention.
All of this is colossally wasteful. If we could turn back time or wave a wand and all adopt the same system it would save a fortune in car and road design and would eliminate the accidents caused by confused tourists.
This is a real issue as we all find out when driving abroad in places like France. Even as pedestrians we are programmed to look in the wrong direction for approaching traffic. Every year there are incidents and sometimes tragedies involving tourists that you would strongly suspect are caused when people react in a split second and swerve in the wrong direction.
There are a few countries that have changed from one side to the other. Canada did so in the 1920s when it was a much simpler affair than it would be now.
Sweden, nominally unconquered by Napoleon, stayed on the left until 1967. The enormous effort that was involved in making the switch had them in chaos for many years despite the fact that most of their cars were already left-hand-drive. Iceland followed suit in 1968 and had a similar experience.
In a rather singular example, Samoa changed in the other direction as recently as 2009. The tiny pacific nation has close ties to Australia, New Zealand and Japan and wanted to be able to use second hand imports from those countries.
I read a British estimate from a good few years ago that put the cost just of changing the road signs at four billion pounds. Just for the signs. You then have to deal with the fact that every single vehicle on the roads is obsolete, even dangerous.
Road markings, one way systems, traffic lights, everything has to be changed. All the buses would open out into the traffic. And of course the whole population has to change the habit of a lifetime.
So we soldier on on the left and cars cost more in consequence. Yet it may be a consolation, when next you buy a right-hand-drive car, to reflect upon the fact that this time we're right and everybody else is wrong.