I picked this up from a web site...
DRIVING ON THE LEFT / RIGHT
The origin of the rule of the road dates back to how people travelled
in violent feudal societies. As most people are right handed it made
sense to carry any protective weapon in this hand. When passing a
stranger on the road, it would be safer to walk on the left, so
ensuring that your weapon was between yourself and a possible
opponent. Jousting knights would hold their lances in their right
hand, therefore passing on each others' right.
Revolutionary France was to overturn this historic practice, as part
of its social rethink. Their military general and self-proclaimed
Emperor, Napoleon Bonaparte was left handed, therefore his armies had
to march on the right so he could keep his sword arm between him and
the advancing enemy. From this time any part of the world that was
colonised by the French would travel on the right, the rest would
remain travelling on the left.
So it would appear that the reason a large proportion of the world drives on the wrong side of the road is down to a short French man - who had a bit of influence - being left handed!!
