I've noticed that the rubber seals at the back of the roof line are missing and perished (RHD L322). I've looked for this issue in other posts but not found anything similar yet (so apologies if I have just missed it), I also can't find anything related in the workshop manual.

Bad news is that you can't buy the seals separately. I took the covers off and managed to glue them back in place but the rubber is rotted and are looking shabby again.
I've been looking for some suitable rubber profile to make some new ones.
They are only a finisher seal for looks. You won't get any leaks from them.

That’s good to know thanks, though I sense it’s going to really annoy me not being able to make it ‘cosmetically’ pleasing. Current: Range Rover L322 4.4tdv8, Porsche 911 (996) Carrera 2, BMW 535d Touring, Skoda Fabia, BMW S1000XR

I'll let you know when I've found something. Got to spray my covers so I'll be putting something on them.