A quick image search makes me think that you found a Giant Grey Moth friend if you're in the UK.
The bit dragging behind its abdomen is confusing because the picture is hella blurry. My guess is that it could be one of two things.
1. Moths of that size and type make cigar butt-looking cocoons. Maybe it's quite young and has some material scraps still stuck to it?
2. Maybe it's dying and some asshole bird or bat caused damage to its tiny intestines without properly being able to eat it so those are just kind of dangling there.
I'm not there in person, but if the texture is dry and paper-like, I'd guess the first. Damp and squishy would make the second, sadder one more likely.
here is an other pic for you guys
actually i took these pics this summer (and no its not from the UK )
i think its Agrius convolvuli. like he said
it's a moth, you pansy. they're the bunnies of the insect world.