hi, by request here it is. I think Wendy Campbell attempted to get this ID'd at the time. Not a good photo but there were lots of them - photo taken 8/7/2013.
The moths were on the part of the reserve north of the M40 (access via the old A40). When you go from the carpark you go down through the wooded area to the foot of a south facing steep hill that looks over the M40. Go up as soon as you get out of the wood and they were on the steep part - lots of rock rose there.
Mark Griffiths, Garsington, Oxford.