Richard you are the one who is making the claim - I'm asking you to back it up.
It's quite apparent you cannot find such evidence because it doesn't exist. It's a number plucked out the air so you, and others, can pretend Virgin Media are "bandwidth constrained" when in reality they are not.
If you are using the post on this page:
https://forums.digitalspy.com/discus...-channels/p142
To back up your claim then that isn't even close to what it says - "based on the current configuration" when Virgin can drop on/off frequencies that aren't in use or change their purpose (TS-ID 38-41 in this case).
It doesn't quantify the unused frequencies in the range, how many additional channels could squeeze in to the existing frequencies or the fact that (in my area) at 10 of those in use for TV are in 64QAM mode, when 256QAM would release 130 Mbit/s for new channels - more than 14 HD channels given they squeeze 6 into 51 Mbit/s.