According to the 'Variety Movie Guide', director Peter Hyams drew his inspiration for this movie from the Metro-Goldwyn-Mayer wartime romance, Waterloo Bridge (1940) as well as other films of that ilk. As such, both film's use a place which acts as both its movie title and the physical location setting where the two wartime lovers meet and begin their brief encounter, "Waterloo Bridge" in the earlier film and "Hanover Street" in this movie.
The Hanover Street of this film's title refers to a real street of the same name in Hanover Square, Mayfair, London, W1, England, United Kingdom. A number of streets meet at Hanover Square. They include Brook Street, Dering Street, Hanover Street, Harewood Place and Princes Street. Hanover Street also links upper Regent Street and Brook Street.
In the movie, Lesley-Anne Down rushed out of a Piccadilly line tube station called "Hanover Street". In real life there was no such "Hanover Street Station", at least at the time the movie was set. The nearest train station to Hanover Street today is the "Oxford Circus Tube".
In the end credits, it is listed that Harry Rabinowitz conducted John Barry's score. The reason for this is because at the time of the recording, Barry was living in America, and was not able to fly to England to conduct the score, where it was recorded for financial reasons. So what is mostly heard in the film is Barry's score as it was originally written, because Rabinowitz did not want to touch Barry's score, and Barry couldn't provide any rewrites. Another problem arose with this situation, because Peter Hyams, the writer and director, did want rewrites for the last half-hour of the film. Arrangements were made, and, with the exception of one cue heard during the scene with Christopher Plummer's and Harrison Ford's characters discussing Margaret in the top of the barn, new music was written for the scenes that happen in France. This was also the first time John Barry had a score recorded in CTS Studios' new location; The Music Centre in Wembley, England. All of his other scores recorded in CTS Studios were recorded at their previous location in Bayswater, London.