Thanks MTJL,

I will try a longer time period. In fact, I'll go and do it right now! Thanks

For anyone who is still reading this...

2nd Yoghurt attempt no better! Hasn't solidified at all! There was a few blue spots in it which were also there in the spoon when I looked at the spoon I stirred it with ( I thought it a little bit of fluff) and I am wondering if it has introduced something into the mixture that inhibited it.

I am out of greek yoghurt too, now, to try it, but I do have some normal non-fat plain yoghurt that I could try again with.