In reply to wolfbane:
Seeing that all you need is a grid reference usually with your GPS, so a Garmin Etrex 10 is ideal if your happy to use your GPS in conjunction with a map, it has a good receiver so will pick up a signal in most areas like deep valleys and woodlands. If you are happy to apply the Grid Reference to the map then this is a good unit and is low cost, less than £90.
If you fancy a bit better than the Etrex 10 then I use a SatMap to record my routes, its got OS maps 1:50 or 1:25 (mapping can be purchased as a bundle with the unit and SatMap also sell A1 refurbished Active 12 units at a reasonable price too) and you can relocate even quicker with a SatMap, especially if the weather is really poor or too windy to get a map out. If you accidentally go out without the SD card in the unit, it could be possible, you can still get a grid reference and your route will be saved to the internal memory. If you can get a good Active 10 unit, this in my opinion is a better unit than the Active 12, its quicker with the functions like editing the route mapping or coping files from internal memory to the SD card. You need to keep Internal memory free of any .map/gpx files as it affects the units resources if it starts to run out of memory.
You can get a pro-shield for the SatMap which keeps it safe from being accidentally dropped on rocks or submerged in water, it just bounces about like a ball.
I have both Garmin and SatMap units and over all I'd probably say for versatility the Etrex 10 is pretty good, being low cost, uses 2 x AA batteries, water resistant as standard, simple to use. If you put a way-point into it and you move the pointer to the way-point on the basic map screen you'll get a bearing displayed by the unit (most GPS's do this by the way), you can use your compass then to walk on that bearing, so its a good little unit.
L