There seems to be a bit of a rumpus in Little-Britain-land because some of us aren't very happy with their parody of transgendered people.
I think I should relate my first encounter with Little Britain as a trans person. I'd always been pissed off with the trans characters (and LB in general, but that's just 'cos I don't find them 100% funny), but since we're talking about them as perpetuating a negative stereotype then here's a concrete example.
One of the first people I came out to as transgendered other than my wife was my doctor. Let me set the scene. I'm a huge bloke sitting in front of him, my wife is beside me, I've not slept properly for a couple of months and my life is starting to come apart at the seams. I'm sure most trans people will have a similar end-of-tether story about the time they had the Long Chat with their doctor. It's a pretty serious time for me, having to tell him the reason why I've come to see him.
His response? A Little Britan joke involving the "L" word.
Yes, that's right, one of the catchphrases of everybody's favourite transphobic arseholes.
Now I'm not trying to have a go at my doctor here. He genuinely is a nice bloke and my response: "Within the community they are seen as an outdated and insulting stereotype" he took on board immediately, in fact his instant backpedal was almost comical. He thought he was lightening the tone of a serious moment. I am his first transgendered patient and since then he has been better than excellent. The point I'm trying to make is that Little Britain have done such a good job of putting their characters into the mainstream that not even someone whose job it is to know better was aware that they are offensive to us. Think about it, I'm an in-yer-face kick-arse big bastard of a tranny so I shook it off, but some people having the same conversation are literally on the edge. I'd left my suicidal stage behind by then in coming out to my wife, but a Little Britain jibe at the wrong time could be all it takes for some poor souls.
So there y'go, if anyone in LB-land claims they're all right really and it's all a bit of fun, there's why it isn't and they're not.