I've seen many different butterflies in the last few days – notably Peacock, Comma, Speckled Wood and Brimstone. But this critter hanging upside down in my porch overnight confuses me. I've inverted the photo for more natural viewing.

Obviously I only have the underside of the wing to go on, but I figure it should be on my favourite butterfly reference pages at ukbutterflies.co.uk. However I just can't quite find a match for the markings and wing shape.

I'm assuming it's not a moth because it's resting with its wings up, however I also notice this beastie has no knobs on the end of its antennae, which would classically indicate that it is a moth. The body looks a bit mothy to me as well.

If it is a butterfly the closest match I can see is perhaps a Small tortoiseshell. I'm not at all convinced but I don't know what degree of variation there is amongst them. I'm strongly suspecting that it's a moth out to fool me. Do you know what it is? Please leave a comment or email me with your thoughts.

Update: @Max_Wildlife responded very quickly on Twitter to suggest that it is an Early thorn (a moth). I think he's right. Presumably a female because it lacks the fuzzy antennae.