I always figured that Britian being a seafaring nation they copied the port side/starboard side configuration used on boats and adapted it to highways. After all the red/green light system was originally used on boats and in harbors too.
Some will think this blasphemy, but if I'm correct we Americans actually drive on the wrong side of the road since the presidence had already been established for many centuries in the nautical world.
Steve

Approach life like you do a yellow light - RUN IT! (Gail T.)