Okay, maybe I am dumb, but I finally found the answer! Somehow, (and I did NOT do this), the 'Do Not Disturb' setting had been selected! I did not even know this thing was available (suspect it came with ios6).
But, the strange thing is, I had taken the phone in to the local Apple store here in Castle Hill, Sydney, and they didn't spot the thing was on, and had done a complete restore and told me that if that did not work I would have to buy a new phone as mine was 2 weeks out of warranty!!
Am I going to enjoy telling them!