If the psychotic computer in 2001: A Space Odyssey had you rethinking your relationship with your pocket calculator, spare a thought for director Stanley Kubrick, who feared the storyline would get him sued. 

The film, shot at MGM Studios in Borehamwood in 1968, features a sequence in which HAL 9000 – the ship’s computer – begins killing off crew members.

But just before the film was released in August 1966, the late director began to worry about how IBM - who were briefly mentioned in the film – would react to the film’s closing minutes.

Eager not to displease the leading computer manufacturer, Kubrick – who is ironically known for his controversial films – penned a letter to Roger Caras, the vice president of his production company.

In the letter, written on August 13, 1966, he wrote: “Does IBM know one of the main characters in the story is a psychotic computer?

“I do not want to get anyone into trouble and I do not want them to feel they have been swindled.

“Please give me the exact status of things with IBM.”

The reply – addressed to Kubrick at the Elstree Way studios – came on September 13, 1966.

An excerpt reads: “The name IBM is never associated with equipment failure and IBM’s position is that if IBM is not associated with equipment failure by name, they have no objection.”

The film, which starred Keir Dullea, finally hit the screens in October 1968 and a sequel – 2010: A Space Odyssey, was released in 1984.