Why do drivers in England drive on the left side

We all know for sure that in the United Kingdom you drive on the road on the left. But do we know that to this day drivers drive on the left in another 74 countries and in 1919 even drivers from 104 countries, including Czechoslovakia, drove on the left? But why is it that people in Britain and other countries drive on the left?

Not surprisingly, many of states that drive on the left were part of the British Empire. But not all of them. These countries include, for example, Japan, Thailand, Indonesia, Nepal, Macao and Suriname.^[1]

Coincidentally, the first verified official document regulating the side of the traffic was from England, dating to 1669. It required a patrol to be set up on London Bridge to control the smooth two-way traffic along the bridge. However, it was not until 1765 that left-side traffic on this bridge was legalized. In 1835, this law was extended to major roads and later to the entire British Empire.^[1]

There are several theories as to why drivers drive on the left or on the right, and in fact we do not know exactly why this is the case. Historically, people drove differently and later even different areas in the same country decided the direction of traffic according to their own, which began to unite mostly at the beginning of the 20th century. In support of the right-hand drive, it is stated that the saddle was placed on the left and the horses were guided in the same way. To keep the animals separate, they were led on the right side of the road. In support of left-hand drive, pedestrians are said to have had a dominant right hand free for possible defense. Another theory to support right-hand drive is that the coachman was sitting on the left side because the dominant right hand held the reins. To make it easier to control the car, ie it was situated in the middle of the road, the car had to lead on the right side of the road.^[1][2]

People drive in different countries one way or another. Approximately 35% of countries, like the United Kingdom, drive left, despite the fact that approximately 90% of people are right-handed. Maybe the theory in the paragraph above is behind it, maybe some other, or this fact was rather coincidental. We probably won't know the real truth anymore.