Yikes.! It does look a bit like a body doesn't it! I'm sure it didn't when I was falling around on the inside trying to find something stable to stand on, but I'd better check in the morning! If it's gone in the next photo then you've not seen me, right?!
Out of interest I rang the Bucks railway place, Quainton (as I'm local), and the Bluebell Railway (as I'm originally a Sussex lad) - neither were interested in a free rotten goods van! Guess it'll have to remain my own little project for a while yet (crime scene permitting

)!
Cheers
Pinsanon