Got more time at the Focus, stripped out the fuse box/GEM from under the dash.
Found one of the multiplugs scorched and corroded, tried cleaning it up but the pins on the fuse box were loose and damaged.
So off to the scrappies
Scored an exact match for only £20 !!
Hooked up the new fusebox/GEM and everything works fine
EXCEPT THE IMMOBILISER !
Checked the Haynes manual and it states a new GEM will require re-programming by a dealer/specialist.
Phoned the autoelectrician who says yes he can do it and to call back Monday.
Fingers crossed.....