Hi Dick
I've got there in the end
Tried updating Windows, Norfon and Wetern Digital
No Effect
Tried going into recovery mode with external hard drive connected and disconnected
No Effect
What else to try. Went back through your previous posts and saw the reference to USB connection
My external hard drive has a tag on it saying USB 3.0 compatible with USB 2.0
Looked in Laptop manual and found I have a USB 2.0 port on the left hand side and 2 X USB (2.0 OR 3.0) ports on the right hand side.
Vaguely remembering a previous post regarding issues with USB 3.0 I swapped the external hard drive to the USB 2.0 port
and HEY PRESTO there it was
So, after 3 days of watching paint dry, a comparatively simple solution
Thank you very much for your kind assistance
Best Regards