In your head, take yourself back in time to 1961. Films that are now PG-rated, have an X certificate (such as this one). The world is coloured entirely in black and white. The threat of nuclear weapons and the dangers of testing are a constant risk. And the Daily Express is a reputable newspaper and a bastion for celebrated journalism.

It is in this archaic and unthinkable context that ‘The Day The Earth Caught Fire’ is set. The film was made near the peak of the Cold War – just one year before the Cuban Missile Crisis – and taps into commonly held nuclear fears.

Peter Stenning (portrayed in an excellent performance by Edward Judd), is a Richard Burton-esque, alcoholic journalist at the aforementioned Express. He’s a bog-standard reporter reporting on bog-standard events. His latest assignment is into a plethora of sunspots (meanwhile US and USSR nuclear tests are not deemed unusual or newsworthy). He has a theory that the sunspots, and corresponding strange weather events and seismographic readings around the globe, may be linked to nuclear testing. The film follows him on his investigation, tracking down government scientists who know the truth, only to discover that the earth has been knocked off its axis by two simultaneous nuclear bombs.

The key to the film’s success is the script, co-written by Wolf Mankowicz and the director, Val Guest. You may (rightly) be thinking that the plot described above is as unbelievable as the Daily Express being a reputable newspaper. And you’d be right. Many sci-fi-disaster movies suffer because the audience knows that the science is bollocks – think of “mutating neutrinos” in 2012 (Roland Emmerich, 2009) or just about anything in Armageddon (Michael Bay, 1998). On the other hand, if ‘science’ is done ‘correctly’ (i.e. an effort has been made to make it believable), you can get Jurassic Park (Steven Spielberg, 1993).

It is this latter category into which The Day The Earth Caught Fire fits. Watching a scientist seem genuinely confused that the motion of the planets is, for the first time, not aligned with what Newtonian physics predicts gives a genuine chilling dismay. By following an investigative reporter, adding to the story piece by piece, there is never an (overwhelmingly) implausible jump made, allowing the film to get away with its unbelievable plot. The co-writers must be credited for creating this excellent narrative device.

But as well as the overall plot, the script is similarly excellent because of the quick-paced, screwball, Sorkin-esque dialogue. Down-trodden, alcoholic journalists throw jibes at each other, blaming others for their mistakes: “I was under pressure and sober at the time”.

A large part of the joy of the film is seeing old-fashioned journalism in action. The portrayal of the profession is completely believable. Journalists moaning about being given poor stories, the large scale printing machines being called into action, and journalists being semi-permanently stationed in pubs, all add to the realistic atmosphere. These antiquated methods were the way in which newspapers used to operate in years gone by (or how I imagine Private Eye operates to this day).

There is a very good supporting performance by Arthur Christiansen, as the Editor of the Daily Express. Christiansen himself was not actually an actor by trade, but a man who’s day job was … Editor of the Daily Express.

The London setting and genuine local accents adds a further air of believability to the film. For instance, the London accents of many of the supporting actors sound just like Michael Caine. There is even a police officer who seems to be doing an out-an-out impression. (Note: turns out that it was an uncredited early performance by Michael Caine).

While much of the 1960s atmosphere is to the films commendation, a couple of aspects of the film have dated badly. Some of the special effects are very ropey. Many were created through ‘matte painting’ – large scale paintings of London, onto which events could be created. There is some affection towards the amateur nature, but largely they are just quite poor. And secondly, while the film is quite racy for 1961 – seeing an extra-marital affair, for instance – there are a few too many unnecessary shots of women’s bottoms.

These however are minor details in contrast to the success of the film as a whole, as a British sci-fi classic. And the key to the success of the film is that it is believable, even throughout its unbelievable plot.