got it. The common feature of Warriors’ Gate, The Power of Kroll, The Pyramids of Mars, Planet of Evil, Revenge of the Cybermen, The Mutants, The Abominable Snowmen, The Moonbase, The Smugglers and The Rescue, plus, in its own special way, The Edge of Destruction, plus arguably The Deadly Assassin, plus as points out The Sontaran Experiment, is that there are no female characters apart from the regular cast. (The Edge of Destruction has no characters at all apart from the regular cast; The Deadly Assassin does have a woman actor, but she does not play a female part; queries The Rescue on the basis that Vicki is not a regular at that point, but personally I think companions count as regulars from their very first episode (Nyssa/Keeper of Traken, not Logopolis; Ben and Polly/The War Machines, not The Smugglers).

There are a couple of other stories from the classic era where there is only one female guest character who gets only a couple of lines – The Three Doctors, The Tenth Planet, and Castrovalva come to mind. It’s impossible to think of that happening in the Russell T Davies era, isn’t it?