Did Doctor Who just tease the spin-off show we all want to see? Will Bill be back?

Well now we have some answers. Following the Doctor Who series ten finale, it looks as if Mackie has left the show (to be replaced by an as-yet-unknown new companion selected by incoming showrunner Chris Chibnall). But Bill lives on, jetting around the universe at light speed with her university crush Heather, in the form of a hyper-intelligent alien engine oil…

Ok, yes, probably time for a refresher…

As you may recall, we first met both Bill and Heather in series opener The Pilot.

Heather – played by Peaky Blinders star Stephanie Hyam – was a student at the university where Bill worked serving chips, and there was an instant attraction between them.

Heather could travel fast and she could travel in time. And at the end of The Doctor Falls, with Bill believing the Doctor to be dead, Heather returned to free Bill from her Cyber-prison and they headed off on a new set of adventures in space and time – but not before Heather gave Bill another option...

"I can make you human again," said Heather. "It's all just atoms, you can rearrange them any way you like. I could put you back home, you could make chips, live your life, or you could come with me. It's up to you Bill, but before you make up your mind, let me show you around."

"Just one thing," said Bill. "I've been through a lot since I last saw you. So I'll show you around."

And off they went.

So a goodbye to Bill, which is a shame because she was a great companion, but also a happy ending for her – if it is an ending...

...because the door has certainly been left open for her return.

Heather found Bill again thanks to a tear – a droplet of herself that she left with Bill, which allowed her to track her down. And now Bill has done the same with the Doctor, crying liquid-spaceship tears of her own on to his face.

"It's a big universe but I hope I see you again," she said, before repeating the Doctor's words to her, "where there's tears, there's hope..."

Pearl Mackie didn't get as long as she deserved in the Tardis, so it would be nice to one day see her back again for a cameo.

In fact, I wouldn't be at all surprised if it happened before the year is out...

Just think: Bill hasn't be introduced to the concept of regeneration and currently thinks the Doctor is dead. If he finds out what's happened to her, no doubt he'll want to see her again, to reassure her that he's ok, to make sure she is, and to say a proper goodbye.

Showrunner Steven Moffat, Doctor Peter Capaldi and companion Bill Potts all bidding farewell in the same episode, and at Christmas no less. That's bound to tug at the heartstrings.

In the meantime, though, here's another suggestion: a new series about a pair of adventurers in space and time...

Forget Clara and Me, surely Bill and Heather is the Doctor Who spin-off we all want to see.

And we have just the title: Stars in Their Eyes.