Having bought the car 200 miles away I think it's a bit of a faff trying to get the dealer to replace the lamp (although something that hadn't crossed my mind). I'll just buy another from VW parts.
Still baffling as to why it's missing. No point with a pic as all you'd see is a blank hole behind the OBC and a [retrieved] dangling wire. Not the most interesting of pics

Thanks for the responses chaps - much appreciated (as a newbie here)
(if it turns up under heavy breaking I'll let you know!)