(World Productions/ITV drama serial, 2012) Absorbing thriller set in 1952 but guilty of a number of anachronisms. Relevant here is an RML class AEC Routemaster, a type not built until 1961. The registration plate is unclear, but it may be a 1966 example.
We see only this interior in episode 1 - I am assuming it's the same vehicle as seen in episode 2:

A night external view in episode 2: