Thirdly, why are you making things up about spectrum planning? There is no need to waste 18.8 Mbps of capacity for "spectrum planning" purposes. Even if you did need to save capacity for moving channels around (which you don't - why would you want to do that?), 18.8 Mbps is enough to carry 4 x SD versions of BBC1, and the most you'd need to leave over is enough capacity for 1 version of BBC1. So, again, you simply didn't want to admit that there is plenty of capacity on the transponder that could be used to increase the bit rate of BBC HD TODAY if you wanted to, but you CHOOSE not to improve the quality - come on, admit this, please.
"It costs £7million a year to broadcast [a TV channel] over digital terrestrial, good old fashioned masts and antennae. It costs a tenth of that to run a channel over digital satellite, and a tenth as much again, just £70k, to run a tv channel over the internet."
So as the bit rates of BBC HD will be about the same on Freeview and satellite, the BBC will be spending 10 times as much to transmit BBC HD via Freeview than via satellite.
The BBC has 231 Mbps of capacity on satellite (7 full transponders), as opposed to having just 36 Mbps on Freeview. It is quite simply dishonest to suggest that the BBC needed to reduce the bit rate of BBC HD on satellite when you consider the amount of capacity it has at its disposal - not to mention the fact that the BBC wastes 18.8 Mbps of capacity on the satellite transponder that BBC HD is transmitted from!
The ONLY plausible explanation is that the BBC chose to degrade the picture quality on satellite down to the level at which they would be forced to deliver it at via Freeview, due to spectrum constraints on Freeview, and that's because the BBC is biased towards Freeview.
Greg Dyke admitted in the book he wrote after leaving the BBC that the BBC viewed Freeview as their way of hanging on to the licence fee for another 10 - 15 years because it allowed them, in Greg Dyke's words, "to flood the market with dumb set-top boxes", i.e. set-top boxes that don't have a card slot to enforce conditional access, which ruled out subscription payments being taken.
Also, Freeview isn't satellite, and the BBC hates Murdoch, because Murdoch hates the BBC. This is also why the BBC chose to delay launching Freesat for about 5 years - they first said they were going to launch a free satellite platform, and they even registered the name Freesat, back in about 2002, but they then waited until just before the first TV region was about to switchover before they actually launched Freesat, and when they did it hardly received any TV advertising in comparison to the very high profile TV ad campaigns the BBC runs for its preferred platforms - the vast majority of BBC TV adverts for digital TV switchover focused heavily on promoting Freeview, because that's the BBC's preferred digital TV platform.
If the BBC gets away with doing this it would be a disgrace.
* BBC HD - 9.8 Mbps * channel 6945 - 9.8 Mbps * null bytes - 8.8 Mbps
So even if the BBC launched a 2nd HD channel tomorrow it would still have the 8.8 Mbps of null byte at its disposal to increase the bit rates of BBC1 HD and BBC2 HD by 4.4 Mbps each.
Also, as paul_geaton has just said, the BBC isn't planning on launching a 2nd HD channel until 2012 anyway.
As things currently stand, the BBC had absolutely no reason whatsoever to reduce the bit rate of BBC HD on satellite, so the only plausible explanation is that they did so because they're biased towards Freeview.
2. The satellite transponder that is carrying the BBC HD channel has about 8.8 Mbps of capacity unused (referred to as "null bytes" on the figure linked to) plus a channel "6945", which carries an identical audio-video stream to the BBC HD channel that people watch on satellite. I've asked what the purpose of this channel 6945 is, but nobody knew. So as things stand, the BBC is definitely wasting the 8.8 Mbps of capacity on that satellite transponder that consists of "null bytes", and the BBC is possibly wasting 18.6 Mbps if channel 6945 is serving no useful purpose.
If you combine both of the above two facts, the BBC is indisputably deliberately degrading the quality of the BBC HD channel on satellite (because the BBC is wasting bandwidth on satellite, and quality always goes up if the bit rate increases).
The fact that they chose to do this a few months before the BBC HD channel launched on Freeview, where the BBC HD channel has to use low bit rates due to the capacity constraints on Freeview, and taking into consideration that Freeview is obviously the BBC's favoured digital TV platform, the only plausible explanation IMO is that the BBC has deliberately degraded the quality of the BBC HD channel on satellite because it doesn't want satellite viewers to watch the channel at higher quality than it's available at on Freeview.