I suspect Green Wing is shown on BBC America though, yes? Like So Graham Norton and Spaced (I think), Channel 4 programmes often get shown on BBC America because of a deal they have with the BBC. Basically the BBC is funded by the licence fee and the goverment and so carries no advertising. ITV and Channel 5 (plus most of the satellite stations) are private companies that geta teeny amount from the licence fee but primarily are funded by advertising. Channel 4 is a slightly odd entity in that while it does raise revenue from advertising it also gets a fair amount of it's money from the licence fee and the government and a lot of it's prgrammes are either filmed at the BBC studios or have some BBC input. The same thing is true of S4C (the Welsh language version of Channel 4). So you'll often get shows on BBC America which aren't actually BBC programmes because they were made by Channel 4. Assuming that they're all made by the BBC isn't an ucommon mistake and pretty understandable really.
As for England/Britain... tut tut, very bad form old chap. It's like saying 'Texas' instead of 'USA'. Or, well, not really, but sort of.
And Green Wing.... absolute bloody genius. It's complete mayhem and incredibly silly but just some of the best TV for years. Channel 4 do seem to hit the mark more often than not with their comedy (Spaced, Father Ted, Green Wing, Black Books, The IT Crowd, Smack The Pony), possibly because the writers and cast are given mroe free reign to do what they like. Of course Green Wing also benefits hugely from the presence of the unutterably marvellous Tasmin Greig, who is one fo the finest actresses and comediennes we've ever produced to my mind. Everyone else is great too though, and they clearly had a huge amount of fun making it. A ot of it is improvised and if you w3atch carefully often the reason that they speed things up at the end of a scene is so that you can't see the cast laughing.