Hidden City [1988 feature film]

In Stephen Poliakoff's first directoral feature, the enigmatic Sharon Newton (Cassie Stuart) persuades reluctant statistician  James Richards (Charles Dance) to help her locate a series of wartime films, which she is convinced hold the key to a long-forgotten mystery. Ther search takes them first to the extant northern entrance of the Kingsway Tram Subway (the southern section starting in Lancaster Place was converted into a vehicular bypass in 1964, with a new ramped exit at the junction of Kingsway and Aldwych)....

The surviving entrance to the Holborn tram tunnel on Southampton Row, just to the north of Holborn Tube station. See here for some recent photographs of the location.
Having no luck at the tram tunnel, they are directed to "the shelter on Tottenham Court Road" - i.e. the Goodge Street Deep Level Shelter built during WW2.
The blockhouse over the northern entrance of the shelter, on Tottenham Court Road.

The London Underground in Films & TV

09/03/04 First upload
22/10/17 Hosting transfer & amendments