Sorry Phil it is difficult to be confident from the photo. Waring and Townsend describe the differences at some length, including checking the underside of the wings. Moths count website has a guide to difficult species http://www.mothscount.org/text.asp?PageId=105. The Northumberland Moths website has a section called "id tips" which has comparison photos. There are lots of photos on the Moths dissection website http://mothdissection.co.uk/contact.php. It is always easier to check sources like these when you have the live moth. It does get easier!
Thank you for the links.