It might seem odd to viewers nowadays, but one of the rules Sydney Newman, the executive in charge of Doctor Who at its beginning, put into place was ‘no bug-eyed monsters’. This rule was, of course, broken as early as the second story, The Daleks, but it signified something about the intention of the show when it started – that it was to be at least partly an educational series.

“So let’s all learn about human sacrifice and enforced marriage, shall we, children?”