I had used the AutoGlym kit (from Halfords using S.O.C. discount card) but read about using bicarb toothpaste

These lights on my lads colt had already been subject to the kit treatment but still had a touch of 'cepia' about them so I thought I would try the toothpaste

I did one and then took photos of each to have a direct comparision

Before

After

So - Worth trying a tube of tootpaste before spending £25 or so on a full kit

 

Now you have polished off all the UV protection these will turn yellow quicker. You need to re add the UV protection if keeping car for a long time. You can use transparent vinyl wrap to replace this. Spraying with clear coat can reduce lights performance but will work. When the wrap looks bad just replace it no need to polish again.

That is true - I coat with a wax on completion to provide some UV protection - there was another specific product described on one of the threads that I wrote down and put somewhere safe......🙄