Meridian Treasure Hunt

[Rick]

Somewhere I've got a note of some of the formulae needed to convert between Universal Transverse Mercator and geographical co-ordinates. I forget whether the OS grid is a UTM grid or some other projection though. I do know it's not based on the WGS84 spheroid that's usually the default setting for GPS. I can get my GPS to display OS grid co-ordinates, but it plays merry havoc with the waypoints I have saved for locations in Germany, Kenya and Australia if I make the mistake of trying to save and then restore them....