Lucy the cat brought this in, set it at my feet while it fluttered away and wandered off. It is about 4.5 cm from head to tail, found in the Leeds area at about 11pm (late June). I'm also pretty sure it's dead now, or close enough that it makes no difference.
Yes I agree that it looks like a hawk moth. There are the slightest hints of pink on the wings and the tip of the tail so I wonder if it is an Elephant Hawk moth. I guess the cat has licked off the evidence