[KevinBattle]

Vacuuming the dog hairs and noticed this opening.
It looks a bit unfinished and just surrounds what seems to be a cavity in the seatback.
It also looks as if some form of trim should be around it.

Anyone with a Gen 5 have anything like this?
It most closely resembles (to me) a recess for the seat belt clip, but on the back of the seat?

 

[Bugginbob]

Just a guess but isn’t that where the retaining latch would be for it to lock to the seat beside it? Think it’s 40/20/40 seat split so the middle one would need to latch to both outer seats to stay secure. But it is a guess.

 

[KevinBattle]

Brilliant! Guess or not, that's exactly what it's for!
I'd assumed the locking pin(s) were each side to be released by that central handle.
Tested this morning and hey presto! the locking pin emerged through that slot.
Mystery (to me) solved! Thanks

 

[fenegroni]

That reminds me to get a cover for the whole of the boot before getting a dog