Turns out, on the TV there is a setting under:
Menu -> Sound -> Additional Settings -> SPDIF Output -> Audio Delay
This 'Audio Delay' option was set to 30. I set it to 0 and both the playstation and the xbox were then able to use the TV as an HDMI audio output.
Such an odd thing but that seems to have fixed it
I have had a Samsung TV for the last two months. I think it a 46UE6030
I have been using my PS3 and my XB360 with it with no problems since I got it.
I arrived home from holiday yesterday to find that the TV is no longer accepting sound from either console through the HDMI cable.
The playstation has decided that suddenly "This HDMI device cannot be used for audio output" and the xbox just does nothing.
It's been fine with both up until now. I've checked and both consoles are working fine on my other TV.