Err Humm ....
The man you need to take it to is named Rob Collins, at the Museum of Antiquities. The stone contrasts with one I found at about the same time - earthfast and covered in micro-cups. While stinky Stan came out to identify yours, driving xx miles, he told me to read all his books and then to get in touch with him again. Thus proving that he's ageist, sexist (and a couple of others). My stone gets a tractor cutting bar driven over it every year and is still 'unrecorded'. So I'm still carrying it.