A new rattle/clunking.... any idea's?

[z4alfie]

Before you all groan at the idea of another post about an annoying rattle, I am hoping someone will have an idea what my new 'only over bumps' rattle might be. It started on Sunday (not that I'm saying the day of the week is significant). Comes from behind the passenger seat area, sounds exactly like the metal jack rattling in the plastic gap behind the battery....It wasnt. I have raised and lowered the boot height mechanism...not that. I have checked everywhere I can think of and I am now hoping its not a broken spring (they were replaced at the dealership 10 months ago) as the MOT is due next week. Any Idea's? Ta in advance

 

[Aebous]

Anti-roll bar link worn?
My front left one was worn, and it would clunk and very very occasionally rattle. Not sure how you'd check the rears.