Nick, I can see what you are saying but that just tilts the side screen inwards (which I may have to do, but thats after sorting this issue). Interestingly GoMog says this isn't effective! I need to move the side screen backwards!
Calypso, I've just replaced the perspex windows so getting them in and out isn't a problem. It's new Perspex so a bit more pliable than the old ones (I broke one getting the originals out). I have the hood on at the moment but I have clearance problems at the bottom of the screen as well as the top which isn't affected by the windscreen top being pulled back. It looks like new mounting brackets with slightly different fixing hole positions may be needed to move the whole frame back a few mm. The rear one may need modifying in length. Otherwise I can't see a solution other than trimming back the leading edge rubber. This of course reduces it's depth and some neoprene may need to be introduced into the rear of the windscreen frame.
Where did you source the new sidescreens?