The trouble and strife fixed the problem!
Last Friday I finished imaging at 1.0 a.m in the morning. It was dark in our back garden.
I had to unscrew the Red and Black Mapli power terminals, to remove the power cable. I then
screwed the terminals back on in the dark. You can probably guess - I screw on the RED and black the wrong way
around. So next day back imaging again I used push-in power leads onto the Maplin terminals, not realising
that the RED and black terminal knobs were screwed in wrongly. So I was powering up the board with negative polarity.
Luckily the motherboard had built-in protection from negative power polarity - few.
I am ashamed to say the wife took one look at what I was doing and pointed out I got the terminals reversed - I felt a right wally,
And since then she has not stopped laughing.