walk on the left (?)

In America we drive on the right and walk on the right. So I thought that in London, since they drive on the left, you must walk on the left. Not so. It appears to be a free-for-all on the sidewalks. Walk where you want. However, most train stations have some signs that say to keep left but no one really does it. They also have signs to tell you what side of the steps to walk up and down. Imagine one hundred people getting off a train and going out of the station up their set of steps...but a couple idiots are trying to go down the steps at the same time. That's why they have directions! Things would work so much smoother if everyone followed the system. It just makes sense.