Once upon a time, the idea that the Doctor and his assistant could possibly be attracted to one another, as has been played out in recent series, wasn’t just miscegenation of species, it was…icky.

Look at Jo Grant’s adventures with the Third Doctor. Every time the two of them are discovered, having just arrived somewhere, Jo is the first in with the plausible lie, that this is her uncle and they’re travelling together. Just as she does here, when the cargo ship the TARDIS arrives within is attacked by a plesiosaur.

And that’s the way their relationship always played out. Where her predecessor Liz Shaw had been a scientist, attempting to talk to the Doctor on his own (slightly geeky) level, Jo was a trained UNIT operative whose attitude towards her travelling companion was that of a much-loved schoolteacher. She’s his subordinate, but, crucially, one who teaches him how to deal with people.

When you consider that their episodes were made and broadcast in the very early ’70s, when young people felt that they were privy to secrets that older generations could not fathom, you can see why Jo’s role is so important.

He’s old and crabby; she’s young and engaged. He thinks he knows it all; she wants to find out more. He has the wisdom and arrogance of the ages; she’s got the charm of nowadays on her side. Katy Manning plays this mix of clued-up innocence beautifully.

And crucially, while Jon Pertwee’s aloof, huffy Doctor is frustrated by being exiled on Earth, Jo Grant’s job is to act as diplomatic liaison between him and everyone he meets, including the Brigadier. She smoothes the ruffled feathers on both sides – even between the Doctor and us ­­– by puncturing his superiority balloon at every turn. And always while acting out the traditional companion role, being the person to whom the story is explained, for the benefit of the viewers.

If she wasn’t there, it’s likely the haughty Doctor would have been captured far more often, and consequently would choose to save the day a lot less.

Here’s her first appearance in the show. Undeterred by the Doctor’s pomposity as always:

And here’s a setup we all know well, the classic “Doctor are you sure you know where we are?” This time with added chickens. You’ve got to love how quickly the Doctor travels from peacock sure to baffled to resigned to huffing “oh Jo do come ON.” Jo, meanwhile, takes it all in her stride

Here’s the Doctor being captured by the Draconians (clearly a ruthlessly efficient bunch, with a name like that). And what does Jo do? Convince the Doctor to get off his bench at the beginning, and explain that he’s been captured at the end. Plot, consider yourself driven.

And here’s her sad farewell, getting married to a man eating fungus soup, with the Doctor riding off into the sunset on Bessie.

Who says that ‘Lonely Doctor’ thing started with Russell T Davies?

Next: Sergeant Benton and Mike Yates, the Brigadier’s companions

