have just re-wired it. I decided to leave the humbucker as it was but swap the singles, I'll explain...
I think that having the outer shield of the HB as the +ve connection would provide too many chances for there to be a short circuit as that is exposed along the whole wire and could therefore touch any part grounded part (e.g volume knob) and go to ground.
So anyway, I rewired the 2 singles and it all works fine. I don't know why they were out of phase as the instructions with the singles says that the black are to go to ground and the white to the switch and the Seymour Duncan Website said the outer shield is ground... Which is what I did 1st time...
So now I have it wired up against the instructions but it works...!