Others have expanded on the use of these codes, so I won't repeat them. Just one question is puzzling me though...
Could you clarify - is a mobile phone signal needed, because if it is they wouldn't work out at Silbury.
How would you know? You've said later that:
I admit I've never tried to phone anyone from Silbury
Hahaha! Hilarious ...
What actually I wrote in my second post was this: "I admit I've never tried to phone anyone from Silbury, however, in many of the locations around Avebury my mobile doesn't receive a signal ... which is just fine by me.
Thanks for the info, have also read the other posts on this subject - looks like an interesting development."
Perfectly polite, admitting I might be wrong about the phone signal.
I've phoned people from the top of Silbury, naughty boy aren't i. ; )