Due to a fault somewhere locally I didn't have net or cable tv access earlier. When I found that there was a problem, I checked all the cables (just in case something is loose).
A few hours later I found that it seemed repaired - but I had no sound. A few hours later (and watching a world cup game with no sound) I wondered if I'd knocked a scart cable loose when I checked everything. Sure enough, I had - the sound wire are on the part that is most likely to be 'loose'. 10 seconds later - I have sound.
Wish I realised sooner, I would have liked the football commentary.