That is odd. I wonder what it was.
I think this is the 'ab fulva' form of Little Thorn. There's a similar image on the Hants moths website:http://www.hantsmoths.org.uk/species/1901.php
Well worked out George! I wouldn't have found that.
Yep, that's what I put...but it still looks odd. Maybe an intermediate form we don't know about.