Think about this, The most modern tank in the world is based on the size of the train tunnel. The train tunnel is based on the width of the gauge of the train. The gauge of the train is based on the width of the axles. The axles were based by the width that the coachbuilders built them in the 18c. The width was based on the width of a horse drawn coach. The width of a coach was based on the width of the ruts in the road so as not to break the axles. The Romans determined the width of the road. The Romans made them wide enough to get a chariot down. The width of a chariot was determined by the width of two horses side by side. So you are telling me that the most modern bit of kit in the British army is based on a horses arse. Makes sense! "Bloody Romans"