So what was the issue? Had the same prob and mine turned out to be a head gasket
Before:
After:
A good clean and new O-rings. I haven't had chance to put her back on track yet (weekend after next is her next outing) but after some hard runs up and down the freeway in Mexico she was dry as a bone and seems to also be running a little better. Also replaced all of the fuel lines and there's not a whiff of petrol now.
I appreciate everyone's advice, I wouldn't have known where to even start without it!