Yup. I don't require a TV license, but...
I'm having this argument with them at the moment and have received the "We're going to start investigation" letter which I promptly shoved in the bin, but only after noting that apparently the only way to "stop the investigation" was to buy a TV licence. Which is a pile of totally incorrect threatening boll**ks as I don't actually need one.
So... so far I've had one bloke round who I refused entry to. This was after he threatened that if I didn't let him in they would just send more people round. I replied with a reminder to him of my (and his) rights and a fanfare of "bring it on, you'll soon get the message" and that it would allow me to start to build a nice harrassment case against them. He sloped off.
As a civil collection agency, I categorically refuse to provide my personal details to them or tow their line, and I am very much looking forward to round 2.