The BBC Trust - the broadcaster's governing body - today gave BBC execs the green light to launch a high-definition (HD) channel. But terrestrial viewers will not receive the coverage until 2009 at the earliest - BBC HD will be available only over Sky, Freesat and cable.

Because the industry and media regulators Ofcom can't decide how to divide up the additional spectrum available after analogue switch off, terrestrial viewers will miss out on BBC HD - for the time being. While industry big-wigs want to pile straight into HD, Ofcom has other ideas.

The BBC, for instance, wanted to show four hours of HD content using Freeview's MPEG2 compression now, and then up-spec when the switchover happens in 2012. The BBC Trust, however, wants more clarity in the process of moving to HD, and doesn't want punters to buy equipment now that will become obsolete when analogue TV is finally switched off. Which is probably fair enough.

BBC HD footage will be shown for nine hours a day, and will include programmes from across the Beeb's range. The BBC says around a fifth of HD content will be movies and sport. Which leaves room for a lot of wildlife programmes.

Read the BBC Trust announcement here.