There was once a time when London’s Metropolitan police had nothing better to do than drink tea, help old ladies cross the road and attend choir rehearsals, or so The Blue Lamp would have us believe, but by 1950 those days were evidently coming to an end as a new generation of nihilistic young criminals emerged to terrorise the streets of the capital. No doubt every generation has felt this way—certain sections of the British media clearly still do—but the whiff of pro-police propaganda is never far away from this film.

Fortunately, though, director Basil Dearden brings a great visual flair, showing a keen eye for the dilapidated streets of a city that still bore the scars of World War Two. And even within the film’s straightforwardly moral plot, he brings an air of social realism to the desperate criminals that feels ahead of its time. The final confrontation, which takes place at the old White City dog track, is genuinely thrilling stuff and calls to mind classics such as They Made Me a Fugitive and The Third Man.

The Blue Lamp is best remembered these days for introducing the world to the affable policeman George Dixon, who was resurrected by the BBC five years later and continued to patrol the mean streets of Dock Green into his eighties—no wonder people say that police officers seem to be getting younger—but, like his fellow coppers, he is too sentimentalised here to make much of an impression. The real stars are Peggy Evans and Dirk Bogarde playing characters on the other side of the thin blue line, both adding an air of authenticity to a sometimes fanciful tale. The film is not one for the ACAB crowd perhaps, but it offers a fascinating insight into how Britain and the Met wanted to see themselves in 1950.