Been outside checking for the source of the rattle, the rear seats seem fine. But the parcel shelf was very rattly and with little provocation. I've used black tape on the pivots either side and it has made a big difference. Yet to try it properly on a drive but I'm pretty confident. Not 100% sure but I think the parcel shelf feels more flexible than I recall on the MK7 and the flex was just enough to make it keep knocking at the hinges.
On the other point of this thread, anyone got any thoughts on the Racingline rear chassis brace?