Thanks Lastchance, interesting website. Have you used their Greygate G5 polish and paste with good results.
When I priced the replacement acrlyic they turned out to be quite expensive at around £40 / window. For anyone in the West Country I have now sourced 4 replacement acrylic windows at £24 each. This was from “NU Signs”, Mutley Plain, Plymouth. Hurry though as he did not have a great deal of 10mm tinted acrylic left.