Its aunties car she wants it fixed this weekend.
It alsmost look like spray lacquer was used and or not totally covering the light. Possible front end repair and possible overspray, not sure if that is causing the yellowing.
Watcinhg some videos of lens cleaning., like that last one you send Darren, how shows exactally what I'm seeing, its cheap chiness rubbish, not coated very well. This was at 2:06 in your last video.
I just used this on my CRV headlights and it worked quite well. These kits were £25 online but Halfords seem to have just put the price up! It comes with a bottle of polish/cleaner, two abrasive pads and a can of the protective lacquer. Didn't take too long and has made a considerable difference. Before and after pictures below...
Just been giving that a go. Only done one headlight as the other seemed fine. It was mainly along the top of the light so concentrated on that. I got the kit that had a sanding disk and pads that go on a drill. Started on 800 grit, then 1200 then 2000 using water too. Then polishing compound with the woolen pad on the drill. Dried off, looks very good, the bit I was focusing on looks great. However the bit that looked okay before now shows up worse than the bit I aimed for. No photos though. Applied the UV protection and wow, the whole thing looks like new. Very impressed.