Ended up buying a set of headlights off ebay to replace a cracked one. The lenses were pretty rubbish when they arrived so fitted them and set about restoring them: Wet sanded with 400, 800, 1500 and 2500 grit sandpaper. Compounded with Meguiars ultimate compound finished with Meguairs M105 and sealed with meguiars headlight coating to protect for now