'Move It' by Cliff Richard
Clearly heard this during the scene with Hector and Kiki before she gets beaten up.
Wasn't this recorded in 1958?
And isn't this second series set in late 1957?
I thought exactly the same thing. It wasn't recorded until the summer of '58.
I don't know if these are intentional anachronisms, as they think a certain idea works anyway despite that. Ashes To Ashes had a few. The third series was set in 1983, and 'Walking On Sunshine' was played, the version of which wasn't performed for another 2 years.