Christopher Chung, who played Cassio Palin-Paleen in The Well, says that working with Russell T Davies on Doctor Who was “an absolute joy”.

Cassio was one of the troopers in the Fifteenth Doctor (Ncuti Gatwa) episode, and Chung recalls:

“It was cold, it was wet. I got to wear a space suit, which was great fun, and I got to work on a show that’s so world-widely iconic, which I never thought I’d get to do and to work with [showrunner] Russell T Davies was an absolute joy. I had a great time doing it. And I got to meet Ncuti. So it’s just fun going into a sci-fi, something completely different to Slow Horses. So, I’ve been really gifted with the roles that I’ve gotten to play in between doing Roddy, but they’re all very varied and different.”

The Well was one of the best-reviewed episodes of the last season, and acted as a sequel to the much-loved Tenth Doctor (David Tennant) classic, Midnight.

So was Chung aware of Midnight? He explains that he watched the episode ready for the audition:

“They did send it as a reference. I didn’t realise how iconic it was, but yeah, when people knew that that episode was going to be a continuation and a follow-up, that was really exciting.”

Christopher’s character met a sad end when he tried to assume leadership — only to be inadvertently killed by Aliss (Rose Ayling-Ellis).

And while Aliss got off the planet alive, it’s likely something else escaped with her…

You can rewatch The Well on iPlayer, as part of its Whoniverse section, now.