Another rear wheel arch replacement question

Hi, Disco has just failed the MOT on sills etc etc etc. The wheel arch is rotted at the bottom where it joins to the sill and also at the top where it meets the rear wing so I'm looking to replace the complete wheel arch. Looking a various posts and pictures I realise that its spot welded to the inner wing but can't work out how it's attached at the top where it meets the rear outer wing. I want to do a half decent job so is it 'a rear wing off' to do it properly?:

Thanks all in advance

Si

Its just a bolt at the back if I remember.