Today it would be inconceivable that the cinema of a foreign nation would be viewed as a danger to the security of a country. But this is precisely the scenario in regards to the cinema of Russia. Films from the Soviet Union were not banned outright but were refused certification by the film censors. This meant that these films could only be viewed by members of film clubs. Was there a problem with this? You bet there was. The intellect of the members of film clubs dictated as to whether they viewed these films. It revealed just what politicians, both Conservative & Labour, thought of the population.
Middle and upper class film clubs could watch Russian made films with impunity. This is because they were so well educated that they could clearly understand just what the message of these films was. However, it was different for the working class. They being not so well educated, would just see revolution and anarchy! So the Government gave permission to local councils to use the Police as bully boys, to disrupt the showing of Russian films. They were allowed to use whatever methods they could. As they were not allowed to seize the films, it was a simple message "The working classes must not see these films!" Politicians feared that the working classes would rise up and overthrow the Government, Police, Armed Forces, and then hand over the reigns to Russia! Sounds totally ridiculous, but it is true. The National Council for Civil Liberties sprung up from one of these Police intimidation actions. I came across this information in a book on censorship.
Of all the films that would bring about a revolution, the most famous, and still regarded as one of the greatest of all time, is "Battleship Potemkin" made in 1926 by Sergei Einstein. It is based on a real mutiny. This happened on the Potemkin in 1905, whilst it was docked in Odessa. The crew rebelled against the most appalling conditions on the naval ships and expected to eat rancid food. It caused a massive backlash as the authorities put down the mutiny. Some mutineers were hung, many were thrown into labour camps, and the mutiny did cause so much worry for the Russian Government, as they did have two short wars with the Japanese in 1904 & 1905. The film finally received a certificate from the censors in 1954.
As a footnote, the advert about Crunchy Nut Cornflakes with a pram going down steps is based on the most famous scene in "Battleship Potemkin" in which during a riot between troops and the people, a pram with a baby in it, trundles down a load of steps.