From my friend the half-Polish Hi-Fi freak:

The DAB1 standard that is used for digital broadcasting in the UK is very poor. DAB2 as used in Europe and the rest of the world is better but, if we adopted it, all the existing digital radios would have to be scrapped.
There are truly horrendous reception problems with DAB so it's difficult to see how the BBC could turn off the analogue system without breaching its charter.
Of course, what the government wants to do is to auction off the spectrum for more mobile phones ...
This has been a hotly discussed topic for the last few years in the hi-fi community. Folkies are a few decades behind the leading edge. No surprises there then :-P