Went back to basics. Cannot check a fuse in situ with an AVO mk6 multimeter as probes are to big for the top of the fuse. So took fuses out and checked. All OK. Still no voltage at rear heated window. Took panneling of inside rear pillar and disconnected rear cable loom. Voltage to connector was OK. Problem was with the cable from the rear window to the main loom socket. By moving cablein the rubber grommet between rear door and body made rear window work. Suspect broken cable - had it before on the rear wipers - so in the better weather I will replace it.

 

Thank You for the update !