Some critics accused Trainspotting of promoting drug use when it was released, in 1996, but they couldn’t have watched the whole movie. After a jaunty start, Danny Boyle’s film doesn’t shrink from showing the misery, social destruction and death that results from heroin addiction. The trick of the movie is the way it makes its point casually, rather than polemically – unlike the doom-laden addicts in Christiane F., those in Trainspotting have a roguish charm.

While this may not lead to an accurate depiction of heroin addiction – the gang all look far too healthy, for a start – it does make the film watchable enough to make its point. Trainspotting is one of the most popular British films of the past 20 years, and perhaps the most popular Scottish film ever.

The story takes place in a depressed area of Edinburgh and revolves around a group of heroin users in the late 1980s. The sensitive Renton (Ewan McGregor) is the focus while his friends and fellow users include the would-be drug dealer Sick Boy (Jonny Lee Miller) and the inept Spud (Ewen Bremner). The psychopathic Begbie (Robert Carlyle) prefers alcohol to drugs, and is the nastiest of the lot.

Irvine Welsh is still examining the ways we seek comfort in the face of our own mortality

The film follows Renton’s attempts to stop using heroin and live a more conven­tional life – something that is always stymied by the drug-related activities of his friends. Around him, the lives of fellow addicts are destroyed by heroin. The film’s appeal comes from the way Boyle presents the addicts as proactive anti-heroes rather than passive victims.

Working-class life in the depressed areas of Britain did not offer much hope, and the gang take drugs as a kind of social rebellion. It’s a snub to a society that doesn’t have any interest in them, even if Boyle is careful not to blame society for everything – Renton, for instance, has caring parents. The movie isn’t afraid to point out that addicts take heroin because they enjoy the way it makes them feel, either, and the ecstasy is something they talk about a lot.

Roughly speaking: an interview with Trainspotting author Irvine Welsh

Trainspotting was a book and a play before it became a film. Irvine Welsh, the book’s author, rejected early offers for the film rights because he didn’t want it to be a grim slice of social realism. The title itself refers to a very British hobby of spending one’s leisure time collecting the numbers of passing trains; the hobby appears in the book, but not the film. A sequel, T2 Trainspotting, featuring the original cast, will be released in Hong Kong on March 2.

Trainspotting is on re-release at Broadway Cinematheque, in Yau Ma Tei, Broadway
The One, in Tsim Sha Tsui, and Palace IFC, in Central, from February 17.