We used to have to have a radio licence but that died many many years ago, the tv licence however is there purely to ensure the government has its pet propaganda station ready to serve up its messages without question, of course operating it themselves would cost a few bob so they created a "licence" to ensure we have to pay whether we watch their station or not.
In the past the bbc stood firm on many issues and fought hard to stay out of any controversial government activities but as of late their commercial interests have caused many red faces at the bbc and the introduction of an obvious bias against filesharers who they see as taking "their" material, what seems to elude them is the fact the UK populace has already paid for that material, just like the with recording industry folks are asked to pay again and again for something they in fact already own the rights to, how pathetic and greedy, but hey thats big media business's for you.