Doctor Who series 10 episode 3 sees the Doctor (Peter Capaldi) and new companion Bill (Pearl Mackie) take their first journey back in time together, visiting Regency London at the time of the last great Frost Fair and meeting a giant fish for an adventure called Thin Ice.
However, it's not all fun and games, with mixed-race character Bill concerned about how her ethnicity will affect historical figures’ reactions to her (especially considering slavery is “still totally a thing”, in her words), while also discovering that the past was slightly more diverse than she expected.
Now, series showrunner Steven Moffat has revealed why he and episode writer Sarah Dollard decided to engage with race so robustly in the story, saying they “didn’t see an alternative” to tackling the subject head-on.
"History is always white washed," Moffat told TVGuide.com, in words that are echoed by Peter Capaldi’s Doctor in the episode. "How do we manage to have a diverse cast despite that? The way that we did it was ... [to just] say that you will see people of different colours there.
“In fact, there were. People all didn't arrive in the twinkle of an eye. It is bending history slightly, but in a progressive and useful way."
"Also, it wouldn't be a pleasant place for [Bill] in several respects,” Moffat went on, referring to the racist attitudes of certain characters who appear in the episode.
“Taking that on is just respectful of the audience really. It's a chance to – I'm always reluctant to sound so pious and so do-gooding and all of that. It's useful that these things are talked about. The evil in Doctor Who can sometimes be the evil in our real world, too."
When they watch the episode, we’re sure many fans will come to the same conclusion.
Doctor Who continues on BBC1 on Saturdays at 7.20pm