Well I guess the thread title sums it up nicely, the Senior Moment came back to embarrassingly haunt me again!

I went through the Configuration files and spotted the error. It was stupidity on my part!

I had undefined :
//#define REPRAP_DISCOUNT_SMART_CONTROLLER

Instead of

#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER

That would explain all the anomalies I was seeing. Obviously I had this set up correctly in earlier files, but I guess when I edited one of the newer files I focused on the #define REPRAP_DISCOUNT_ part of the line instead of the whole thing!

Now I can push forward, and barring similar stupid errors, get the printer up running and tuned.

Again Bob, many thanks for your help.

Barry