Martin
First the VFormat – no I had not. It turns out that the VFormat had got reset to 576i, and when I reset it to 1080p all was well on HD reception and the “incompatible signal” message disappeared. Thank you – I feel more than a little silly for not finding that myself.
In terms of the pixellation – there are stripes across the screen, sporadically. However, I need to do more research on this, because I improved the RF signal quality yesterday by taking a redundant VCR out of the input stream. I am going to hit the box hard tonight (metaphorically) by recording two programmes in both SD and HD and see what happens. I’ll post back here if the problems persist.
Many thanks for your help