If you omit the fourth digit it looks about right (based on your description). On Multimap it looks like this...

http://uk.multimap.com/map/browse.cgi?grid=SM818315&scale=25,000

Obviously you'll need the 'SM' at the start (i.e. SM818315). Sorry if I'm guilty of trying to teach Granny to suck eggs.

:-)#

Did you see my thread about CARN? Once they've sorted that out it might be worth taking another look to see whether a site *is* listed at your grid reference (or thereabouts).

K x