I was just saying to Boreades that an eminent archaeologist has emailed some comments to the effect that prehistoric peoples didn't have the technology to map/ navigate wide distances. Prove him wrong!
Just going back to this.. did you see the moon last night? Marvellous; anyway the conditions gave me a chance to look at the longitude thing again and thought it might make an interesting discussion piece:
http://heavenshenge.blogspot.co.uk/2012/11/full-moon.html
If there's any interest in this, I'll prepare up the details showing how I would have done it (there are a few methods though when you think it through). Thought it might be interesting to see how other people would do the same job (no technology allowed apart from things which are naturally occurring.. trees, stones etc)