I am based on the Derbyshire border and can lend you a standard GS screen that is likely to be worse or a MRA screen you could borrow but these are both from the standard GS and not the GSA so I am not sure they fit.
So in order to help anybody else who lives nr Buxton (Derbyshire) or central Manchester then I have a Puig and a standard BMW GSA screen that people can try.