Hi John, Been away for a break so just picked this up. Still no luck tracing the fault, although weirdly since we've been back the signal strength has increased and we're able to watch the TV again (mostly). We had a brand new aerial fitted 3 years ago and the the cable goes straight from the aerial to the youview box, so…
Aerial... plug it into the TV and everything works as it should. Thankfully we don't have any little box tucked away, it's aerial straight through the wall and into the box/tv.