Video: Andrea Dunbar's sad journey through Bradford

Towards the end of her life, Andrea Dunbar would return to her old school to visit former teachers. On one of the last occasions, speaking to her art teacher, she said "I'm getting headaches".

Shortly afterwards, in her local pub, she collapsed and died from a brain haemorrhage. It was five days before Christmas, 1990. She was 29.

Twenty years later, a fascinating new feature film unravels the alchemy that led to this extremely gifted and naturalistic writer penning a trio of hard-hitting plays which took first the theatre and then film by storm.

Artist and filmmaker Clio Barnard had the idea to make a film about Dunbar by focusing on past representations of her and her work. The film that eventually emerged was significantly different from the initial project and told a cyclical tale of triumph and tragedy that brought Dunbar's daughter, Lorraine, into the story. It is this relationship between troubled child and dead mother that underlines what would become the film of The Arbor.

Accidentally discovered and supported by Max Stafford-Clark at the Royal Court Theatre in the late '70s, Andrea Dunbar was described, rather patronisingly by her fans in the press, as "the genius from the slums". Given that her home was the battered Buttershaw Estate in Bradford – considered Yorkshire's answer to Glasgow's Gorbals – the reference to her roots was harsh, but fair.

In many ways, Dunbar was a throwback to the social realist explosion of the late 1950s and early 1960s. Certainly Rita, Sue and Bob Too! made by Alan Clarke in 1986 has echoes of films like Saturday Night and Sunday Morning albeit with a comedic twist. Barnard calls it "Carry On Up the Estate".

The Arbor is both a bookend to Rita, Sue and Bob Too! and a companion piece. These are very different films from very different directors but with the uniqueness of Dunbar's words at their core. For Barnard, who created a magical realist documentary by speaking to Dunbar's friends and family and recorded an audio track that was then lip-synced by her actors, it was impossible to be objective.

"The film opens with the scene of a fire where (daughters] Lorraine and Lisa remember things completely differently," says Barnard. "They have got completely different memories of that exact same moment. It's important that you understand that Lorraine's truth is Lorraine's truth and Lisa's truth is Lisa's truth but they totally contradict each other.

"Everyone's got a different Andrea in their heart. What I tried to do was make that clear. As we were shooting it, the reaction was brilliant. People were incredibly enthusiastic."

A quarter of a century ago, the reaction was markedly different. The release of Rita, Sue and Bob Too! was not particularly welcomed in Bradford. It was condemned as unrepresentative, false, deliberately provocative and racist.

"Maybe the great and the good of Bradford were embarrassed, I don't know," says Barnard. "It baffles me that they should have that response because I think the writing is brilliant. It's really stood the test of time because it's on telly all the time, you can quote lines from it, it has a longevity that's proved those people wrong in a way. It's not racist. It's about racism and if we don't discuss that, then how would we hope to understand it? I think she was unflinchingly honest; that was her great skill."

Part-time bingo cashier Natalie Gavin was plucked from open auditions to play The Girl in The Arbor. The character is, of course, Andrea Dunbar and Gavin was desperate not to resort to caricature or impersonation.

"In the beginning I didn't know a lot about Andrea. Now I've found out a lot more about her as a person. She was fairly boisterous, brave... she had quite a soft side to her. Some of my family knew of her; my dad knew her quite well.

"Being from Bradford, I wanted to represent Andrea the best I possibly could. I wanted to be honest. I found her really difficult because I had to have my own perception of her. And I had to make that a right one."

Last weekend, a plaque to Andrea Dunbar was unveiled on the house she grew up in on the Brafferton Arbor of the Buttershaw Estate. It took 20 years for her to be recognised – something that didn't happen in her lifetime.

Even her old school had an ambivalent attitude to her, preferring instead to ignore her success and fame as if it had never happened. Perhaps Max Stafford-Clark, who directed Dunbar's work at the Royal Court, got it right when he remarked "Andrea made the school, not the other way round".

And her words and emotions continue to provoke vigorous debate.