Small Back Room
IMDB says a lot of it was in Dorset, but Victoria Embankment was also used.
From memory I'd say that perhaps some streets in west London also appeared.
Perhaps if you enter it on the lists some of your regular sleuths will be able to assist. It stars Jack Hawkins, David Farrar, Sid James & Robert Morley. It's a classic Brit-movie about a Bomb Disposal officer, gripping stuff and good to watch.
Best regards, Mark Jenkinson.