Judge Death wrote:
I figured that would be the case, I just wondered if there was some kind of legal loophole given the BBC didn't care enough about the material to keep it in the first place
It was nothing to do with not caring. It was the massive cost of storing something (not just Doctor Who) that there was no way of forseeing would ever have any future value. An episode of British TV in the 1960's was designed to be seen at most twice and then never again.