Thanks Meon, a fair point about the paintwork which hadn't occurred to me.
The main reason for asking the question was that I'm sure I remember reading somewhere that there are replenishing treatments which can be given to perspex screens, which might go a long way to sorting this out : but I can't remember where I saw the info (or whether I'm just confusing it with something else).
The financial option is obviously open to play, but not the point of the question.
Oh, should anyone else want to join the bandwagon and tell me to "chill" ... I did apologise earlier, but if it makes you feel better to admonish me, feel free.
Finally, just in case Danny Boy Blue turns out to be correct, and there's a sudden glut of very low hours pilots flying pressurised aircraft , I strongly advise them not to fly with blemished windscreens. There. All done!
FF
