Wow!
Thanks, ICE in Space you Guys are great.
I put the 50D in the fridge to test this Amp glow theory. The apparition definitely reduced at a lower temp.
I have just discovered the imports of
FLATS (Thanks Marc). Can you believe
DeepSky Stacker cancelled out the artefact when I add some
FLATS frames

.
I'll give this Camera a good workout at SPSP next month.