Well they might have fancy GPS gadgets (always wanted one meself) but they can't do grid references - the one listed for the Dod Law Bucket / Ammo Box is a nonsense -
N 55° 34.611 W 001° 59.290 (WGS84)
British Grid: NU 843 31461
I'd be a bit dubious about opening ammo boxes in the Cheviots meself - lots of live old ammunition keeps turning up.