Most of the Discovery Channels' new material is made in the US, not the UK. Most other channels are exactly the same, mostly repeats, and what new stuff there is made in the US. Sky 1 and Sky Living are about the only channels that do do new stuff that is UK produced. Yes, they do a lot of new imports too, but they have a feeling of being stronger than most other channels. Even Discovery's channels pretty much don't feel like they're on a different level from channels like Dave, or even the CBS channels.
Er what has UK versus UK content got to do with it? They can still be popular and strong offerings even though they're mostly American. Factual is an area that is lacking outside of pay TV and the big 5
Personally the documentaries section is the one genre I miss since I left pay TV and went Freeview and the fuss created when Discovery threatened to leave Sky last year shows I'm not alone
For me its an important thing, the whole UK vs Imports thing. I would want to encourage more new production in this country. Sadly, about 80% of the material shown on the multi-channels are repeats, with the vast majority of new or first run material, being imports, mainly from the US, but also from Canada, Australia and New Zealand. Most of the new material produced here airs on BBC, ITV, Channel 4 or Channel 5 and their various associated channels. Most of Sky's first run output is either on Sky News or Sky Sports, with Sky 1 doing the most new commissions out of the multi-channels.