Thanks for your thoughts gents. I'm reassured to hear that people have used Gliptone successfully.
Interestingly I came across this Youtube clip where Louise from Woolies tells us that if the cleaner brings some colour off on your cloth, it has probably been treated with a water based dye previously.
http://www.youtube.com/watch?v=qYcUe6d8LW4
I'm guessing the Woolies cleaner is not dissimilar to the Gliptone product.
Looking at the grime that was on my driver's seat, I would doubt it has ever been treated with anything, but it's not impossible I suppose.