What is it.....?

Please help i have, what it looks like a lockerable plastic bar in the boot of my 1983 cabriolet .
I have no key for it . What is it for .

I don't think it's standard equipment so perhaps someone had a multi CD changer in the boot or something like that?

Or maybe a door to another world….    

Not a lot of space in that area of the boot for anything as large as a cd changer.  a stash for something comes to mind.  funnny as that is a carboard side cover