Where will I find the earth connector on the windscreen? RHS is not working and I've checked the supply side of the circuit, which is all ok. Everything's good from the +12v supply, the trigger from the AC unit, relay link, cable from fuse box to the windscreen connector. Which leaves the negative strap from the windscreen, don't want to waste time and skin from knuckles. 

The ground point you require is CA50 located on the right hand ‘A’ post below the primary junction fuse box.

Figure 06.1 of this manual refers,

http://www.jagrepair.com/images/AutoRepairPhotos/x2062004en.pdf

Found the ground point, it's at the top right of the screen. Power-in is near the base of the screen. Anyways, the all the connections check out it's the screen that's at fault. Can't even buy a new one because the screen companies require insurance details to replace it. Will have to wait for a big crack.