Mouth without a U

This, according to my pocket book of moths, is a Poplar Hawk Moth. Once it turns from pupa to moth it doesn't eat anything. It hasn't got a mouth. Fancy that. Just here to shag or head-butt light bulbs or whatever moths do.
I thought it was dying (from starvation or wearing itself out?) but after it had been in the house for a few minutes and warmed up the little bugger took off. I say little; it's around 2" wingspan - so it was like having a small Vulcan bomber flying around the room.