Nowadays, Britain and some of its former colonies are almost the only
countries
where people drive on the left. Sticking to the left was originally the
general rule, and was legislated by a papal decree around 1300. Under
Robespierre, France switched to the right, or from my point of view as an
Irishman, the wrong side of the road. This was evidently a gesture of
independence from Rome, and Napoleon imposed the change on the countries
he conquered around the continent.