Ok I’ve just been tinkering with the scene and it still happens even without GI, using the edit cam with just a quick render view. Sorry to waste everyones time before. I have no idea why its happening but I don’t think I’m going to have time to solve it.
I imagine that it’s going to be impossible to ascertain a solution without seeing the scene itself so I think I’m just going to have to redesign it and try and put it out again slightly because I have no idea what it could be.
If anyone has come across something like this in the past then let me know.
Thanks for all your help!