@Pillowjoy
I don’t think it’s just that, though. I think there’s a real strand of anti-intellectualism in UK culture, and part of the reason discussions about not watching tv get such kneejerk responses is that people think that someone who says they don’t watch tv is claiming some form of superior intellectual status. When someone says ‘I don’t watch tv’, what people hear is ‘I’m clever. I’m cleverer than you.’ Which is akin to saying you torture kittens in the public approval stakes.
I agree that there's a culture of anti-intellectualism in the UK (although I actually think that applies in a lot of cultures). I think if you went to most European countries and walked into a home and said "I don't watch TV" you would get similar reactions from many people.
But the fact that you think saying: "I don't watch TV" is a way of saying "I'm cleverer than you" is an admission that this is basically what it sets out to achieve. I do think at some level (whether conscious or otherwise) this is what this statement is designed to communicate. Given that that is the cultural shorthand, perhaps it's not surprising it makes people feel so defensive. It's a bit like other cultural cues which are associated with self-conscious "cleverness" or sophistication. Saying you only eat organic food, or that you could never work for a multinational corporation, for example. It's usually a way of stealthily signalling a) that you "get it" and are in the know b) that your financial or cultural "richness" is such that you don't need to do things which ordinary people need to do.
Also let's unpick the concept of being an "intellectual" a bit. Why should watching TV be intrinsically less "clever" than other pursuits? All human life is on TV. You can watch things that are impenetrably highbrow or absolute trash on the same channel in the same 24 hours. There's nothing inherent to the medium which is less "clever". I've argued upthread that this dates back to the birth of television in the UK and the way people saw it as a mass medium and I can't get away from the idea that this is what it comes down to.
And why should "intellectualism" be the preserve only of those people who seek to distance themselves from the masses? If you set yourself up as someone who chooses pursuits to underline their own status as an intellectual, and in doing so in rejecting things that bring pleasure and information to ordinary people, you can see why this gets people's backs up.