oops !!!
i think he might have sussed it.
He tells me he had proof colours selected (view>proof colors). He unticked that option and it seems to have restored more vibrant colours.
I have never used this option for anything so i didn't even consider it.
Even though it is unticked if he changes the proof colors from eg cmy to cmyk there is a difference (obviously).
We'll see.
Sorry if the post turns out to be a bum steer.
thanks for looking ..
cheers