Toothpaste. Pure & simple. I've spent £££££s on headlamp cleaning kits and other products. Toothpaste works. Quite a bit on the 'net about this. Not sure I've seen it on our Forum before - but may have missed something. Hope this helps and saves someone some money. Barrie.
2017-Jan 2024: 2005 RRS 2.7TDV6. Best car I ever had - until now!
Current: 2018 Ford Ranger Wildtrak 3.2

I use a mop ( polisher ) and a bit of rubbing compound , comes up like brand new
For the lights where the outside laquer has burned away , I use 200 wet and dry , then the mop with compound , same results .