We came across this on the roadside east of Hull. Fixing east and west was important for the modern world because it allowed the creation of time zones. Unlike the hemispheres divided by the Equator, the Prime Meridian is an entirely human creation. It could have been placed anywhere. The vagaries of history meant that the British fixed it. It led to Greenwich Mean Time, fixing 12 noon as the time when the Sun is highest in the sky at all places on this line. That was then applied to the whole country even though the Sun is highest in the sky a little later here. It's been a practical outworking of Physics that has enabled things like timetables to work on a national scale.
