It's still breach of copyright. It works much the same way that you're not entitled to a full private recording of a concert you've attended.
You haven't payed for the Bluray that the episode came on, either; do you think that you're entitled to free copies of all of the BBC's shows on DVD or Bluray?
It costs money to make a DVD, it isn't really comparable.
If it didn't cost anything to run, yeah I kind of would feel entitled to access to archived BBC shows for free.