unless the law's changed as far as I knew it's down to the buyer to ask. If you ask if its had an accident and he says no, but it has then he's in the wrong, but if you don't ask he legally doesn't have to tell you.
Although as it's only a shell I don't know how that'd affect it. there's loads of weird laws around buying car stuff, like the V5 doesn't prove you own the vehicle, you're just legally responsible for it, etc.