Not military but......
The triangulation system on 121.5 at D&D is really quite sophisticated now.
Assuming you are in radio coverage it shows your position (on a PC type display) overlaid on an Ordnance Survey map. The D&D controller can then zoom in and say things like "can you see the church to the south of you", or "do you see the motorway to the east" etc.
Very accurate. Lots of other pertinant information (airspace, airfields, etc) can be overlaid and headings to steer as required worked out.
As mentioned, never be afraid to use the service and if you are ever visiting LATCC, D&D are usually very happy to accomodate a visit from any pilots.
WF.