There's Odstone Marsh (farm?), just to the north of 'Odstone' farm too....
As it looks like you can park near both, I may be able to persuade J that we should have a look/ask when we're next down there. Dunno when that'll be tho....
Odstone Farm shows just how careful you have to be about placenames. 'Od'-stone could easily make you think of an Odin link, but knowing it was once Oldstone Farm buggers that one up.
Unless, of course, Odstone was the proper old name of it and Oldstone is the corruption :-)