Bob the TravelerWilliam III and Mary II were crowned as joint sovereigns of Great #Britain OTD in 1689 https://cromwell-intl.com/travel/uk/national-grid-os-maps/?s=mb #travel
Navigating with the National Grid system and OS Maps
How to navigate using the National Grid system and Ordnance Survey maps: GPS references and simple line of sight techniques for finding your way around Britain. It's similar to the UTM grid system.