Annoying rattle from rear

Hi folks, I've had my 2015 Mk5 estate for 10 months and in the last week it's developed a rattle from the OS rear.

It's fairly constant I've had a look for loose things in the boot cabin space, checked the boot lock, removed and re-afixed the number plate and checked for anything obvious on the exterior / rear wheel / undercarriage and drawn a blank.

before I book it into a garage has anyone had similar or know what this could be, or have any advice of other things to check.

thanks in advance

Mods, sorry I've posted in the wrong forum please delete