Yep the screen from Ford is about £1300 + vat, so what ever my excess (£50-75) on a screen replacement is a bit of a no brainer, but "IF" they won't wear it, i guess i'll have to forget it.
Checked the fuse box yesterday in an idle moment and the 2 (30amp) fuses are in situ, and as they don't seem to do anything else but the screen, i'm assuming the heated screen was replaced at some point with a standard one and the dash switch removed .... how very odd

probably as you say because who ever had the car when it was done didn't have sufficent windscreen cover.