In reply to Bulls Crack:
Yes I did get to the .gov pages, these were helpful in understanding my rights if I was on open access land and did lead me to the Natural England maps.
My problem is that (as far as I know) the OS map shows the area as open access whilst the NE maps don't. Don't want to go into details of things as I'm not sure how the incident will progress - I'd rather email NE/OS/FC and get their combined response as to whether I had a right to be on the land or not. Reason for trying to get a combined response is that if I contact the individual orgs I fully expect to get an 'off the shelf response' unless I can convey that I need a more detailed response.
Never felt more like a Serf before