Little Mix were a pop band in the 21st century.
Bill Potts had a whole playlist on Spotify with songs by Little Mix. When the Twelfth Doctor played one of the songs, Shireen told Bill they needed to talk about her taste in music. (TV: Knock Knock)
Behind the scenes[]
"Weird People", another song by Little Mix, plays throughout the opening scenes of the episode, where Bill and her mates are searching for a house to live in.