Hi Jim
I'm sure we could take a look at some point, but speaking for meself from yer photies it doesn't look at all right to me. I'd reckon the bits you've quoted on your fieldnotes'll be right about it being modern.
It looks to me like someone's 'idea' of a stone circle, or a composite influenced by a few different 'real' circles.
I believe the only Ox circle (remaining) is the Rollrights so I'm not sure it's really sensible to talk about an 'Oxfordshire' type of circ, but just about everything around Ox is built out of oolitic (sp?) limestone - the 'holey' stuff. Which just adds to the suggestion it's not 'real'.
I'm sure Paulus might have a comment too!
love
Moth