Right an update on this one,
Moved the back wheels onto the front, that has made a difference. the wobble now lightly kicks in @ 75, reaching a peak at 80 and then dying down again around 85.
Apologies for my naivety, but what does changing the wheels from the front to the back do/shows ?
Jacked the car up and given the wheels a good rock and theres no loose play.
Typically as one problem looks like its getting better another one rises, i have spotted a nice gouge in one of the now front tires so it looks like that will do with being changed.