Have you tried the plastic cleaners specifically for these rear screens Laurence?

They are quite good, I’ve used this (eBay 391496956911 ) on several Convertibles in the past and it does work. Depending on the severity, you might need several attempts. If you can restore the opaque one then you’ll not have the hassle of trying to stitch in a new one which won’t be easy unless you’ve some experience.

The idea of a solid Perspex screen sounds great but the bulkyness when folded down wouldn’t suit the Cabriolet that well aesthetically. I don’t favour the Convertible for that reason. Even with a Tonneau cover it still appears intrusive to me. The Cabriolet is discreet and neat. Having a plastic folding screen is a small price to pay.

I always ensure the plastic screen is evenly folded across the entire length without kinks thus helping to keep it looking great.

i remember seeing a “wheeler dealers” where they cleaned a screen up with t cut

Laurence, give Jack Smith Trimmers a call in Swansea, he’s a professional upholsterer and soft top manufacturer and his prices are very good indeed. He replaced my Fathers soft top and new plastic rear window on his Alfa Spider for considerably less than anyone else and the job was 1st Class.