On Sat, 05 Apr 2014 16:59:42 +0100, Steve wrote:

The following two photos show the lines quite clearly. I paused the Sky
box for clarity but the lines were still moving even with the picture
on pause:

So they are not on the recording or incoming data stream. I'd reseat
all the cables, especially if they haven't been disturbed for a while
(while 1 year). Though as you also say that the internal freeview
receiver also exhibits the problem I don't hold out much hope of an
external cable fault.

The full power down of the TV and all other boxes/TV's connected
might cure it. HDMI works well but is rather too clever at times and
can get confused. I had and audio L/R swap that I couldn't clear
without a full power down of everything, I might even have had to
unplug everything, power cycle each unit then plug everything back
together.

As a last resort you could try a factory reset.

--
Cheers
Dave.