Legally, LocalH is correct. The wording of the law relates to use rather than ownership; if you're using it to receive or record broadcast TV, emphasis on broadcast, then you are liable for the licence. If you're not using it then it suffices to take a cursory step towards demonstrating that you do not use it - like not plugging it into an aerial, and ensuring that it is not tuned. You'd need to use the epoxy approach in some other European countries that take a different approach to TV Licencing law, but it's hardly worth it in the UK.
The licence requirement deals only with the action - not the capability - of receiving/recording broadcast TV, which has the intriguing side effect that catching up with programs on iPlayer is perfectly legal without a TV licence. Similarly, watching sports shows on the Web as they are being streamed (broadcast) is illegal without a TV licence. And if your fillings picked up ITV, you would have to get a TV licence for the receiver in your skull.
The level of enforcement is variable, as the enforcement is done by 'visiting officers' who are very much like any other rent-a-goon on a small wage, with one exception: a good part of their salary is paid through performance-related bonuses (commission). This gives them an excellent motivation to lie, cheat and generally harrass their way through life ('oh, the law's changed, you need a licence for iPods now. No, I can't show you any proof. And I'm not leaving until you sign this, and if you don't sign it I'll have you arrested and fined £5,000'). They will lie like a rug, partly because they barely know the law themselves, partly because they don't think you know the law, but mostly because they need the money for whatever it is Blattaria sapiens do in their free time.
I haven't had a TV for a decade, so I've had a lot of practice in dealing with TVL enforcement. It's true that the BBC is incredibly popular, but like diet soda, it's an acquired taste. We lost the habit because we couldn't afford it, being students. Having lost the habit, the BBC now tastes like carbonated aspartame.