Thanks eonite, I looked at the node previews and I dont understand it (yet). It will wait a bit till I can  look at it closer.

OK - I figured it out and sorted it so that now I only have to change the numbers at the top, the scale factor and the three components of the offset vector. In this case (0,-40,0). I changed -40  to 0 and it just moves nicely:)
I know it looks more complicated to decipher, but its easier (and less prone to errors) to use.
I made a start in converting it to a meta node and it works, but It isnt set up nicely for having 'published values' so I'll give it another go, and add the brightness/contrast parameters to the top.
(and also fix the 'position' method similarly)
I'm still excited about it like a kid with a new toy:)

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/