Before I happened across my solution I had mailed the Ross Technical bods for their input on the subject. They replied thus....
"
Since the BBC changed the transmission type for their HD channels to increase the amount of data being sent (the same transmission system as Channel 4 HD uses), they left them on the same transponder as they were on before though.
We observed that throughout the last 3 days the channels have repeatedly gone off and come back on again (currently our lab receiver has stopped showing a signal from the BBC HD transponder although it was working earlier today on a couple of occasions).
We cannot be certain how long the BBC HD transmissions will continue to be unreliable."
It seems odd that the channels appeared the moment after I made the change. And even odder that the BBC would be running some sort of ropey signal considering their involvement in the Freesat platform.
A happy fallout of the change is that the signal quality for these two channels now registers at 75% where it was previously 63%.
It would seem that the change to the new format opens up the possibility of maybe a third HD channel (BBC2 HD?).
For those of you who missed the BBC latest mass marketing campaign detailing the changes then you can find it on the very well publicised BBC Internet Blog here
http://www.bbc.co.uk/blogs/bbcintern...annels_on.html
Regards
John