Cheers for the advice.
I've spent a little bit of my detecting time yapping to folk about local history and how they can remember this and that,as you say it's part of the fun
I've just remembered,there was a donkey Derby that use to be in a farmers field in huncoat (might be worth a look).
I was thinking letters or maybe sending a email might be a better way of seeking permission,from the older historical sites, but I can see them just being ignored.