A recent report revealed that paramilitary punishment shootings and beatings have risen in Northern Ireland by 60 per cent in the last four years. One shocking detail of the report that was barely remarked upon was that some parents, turning to paramilitaries for policing, have been voluntarily taking their own children to the gunmen to be punished, drugging them up with alcohol or painkillers first.

This is a horrifying development, and yet, in common with much else to do with Northern Ireland, it has barely registered as an issue within the rest of the UK.

Punishment shootings facilitated by family members is a phenomenon with which I, as a documentary film-maker, am very familiar. In 2012 I began talking to the O’Donnell family in Derry. Earlier that year a local woman named Majella O’Donnell had taken her teenage son, Philly, to be shot by local gunmen.

Majella, her son and his shooters are all part of a community that considers itself to be still at war. They are Republican dissidents and do not feel represented by the Republicans who signed up to the Good Friday agreement on their behalf.

I have made films all over the world but on my doorstep found a story that was more compelling than anything I’d ever previously encountered.

Majella’s community does not believe in the police or the government. Previous decades of what they see as state oppression have not been undone as far as they are concerned. This means that when there is a problem, they seek to resolve it internally.

Philly O’Donnell had been accused of drug dealing, and so that situation was “looked after” from within. Unsurprisingly, the shooting (Philly was “kneecapped” or shot in the back of both legs to avoid an even harsher murder “sentence”) had many unintended consequences and I filmed with the family over the next five years exploring those effects.

I also got to know Hugh Brady, a former paramilitary-turned-community worker in the Rosemount Resource Centre, who mediated between the O’Donnells and the shooters. He and his team carry out hundreds of these mediations on behalf of families and individuals who are under threat of shooting, banishment or death for behaviour that undermines community life. This shadow justice system all happens within the jurisdiction of the United Kingdom.

Making the film was an exceptionally difficult project. It took months of visits before I could begin, as this community is defined by its distrust of outsiders. Many felt isolated. Paradoxically they also felt very controlled. I was repeatedly told that their phones and computers were under surveillance and that I, too, was being watched.

It was almost impossible to plan anything. Appointments were rarely kept. Eventually I realised this was significant. This is a community that considers itself still at war, and these were people so used to conflict that it was a struggle to live without it.

And so arrangements were forever in flux, problems were exaggerated. I never knew who was telling the truth. I saw tiny misunderstandings escalate into shootings and feuds.

Yet every person I met was idealistic and aspired to do the “right thing”. Life is tough in this part of Northern Ireland. Unemployment levels are among the highest in the UK, alcohol and drug abuse are rife, but people still lived compassionately. In difficult times of my own, they offered me advice, and made me laugh.

The resulting film, A Mother Brings Her Son to Be Shot, received its international premiere at the weekend in Copenhagen, at one of the most prestigious documentary festivals in the world, where it has been nominated for an award. The Oscar-winning director Joshua Oppenheimer is now executive producer.

The international interest is in disappointing contrast with the UK. The documentary premiered at the London Film festival last year but as yet, no UK broadcaster has committed to screening it, despite mounting concerns that Brexit could reawaken old divisions.

I can’t help thinking this apathy is part of the same general lack of engagement in the UK regarding Northern Ireland. And it was this disengagement that led to a vote for Brexit that could restore the Irish border, with serious consequences.

Some of the people I met during the making of my film are just waiting for an excuse to return to the Troubles. They have not yet recovered from the conflict, nor accepted that the political process requires them to “move on”. They continue to nurse grievances, they plot, they openly carry arms, indeed they yearn for bigger and better weapons. They miss the drama of war, and the identity it gave them. Their children have grown up with this.

None of this suits the narrative that the Good Friday agreement brought peace to Northern Ireland. The agreement was a vital achievement for all involved, and should be protected, but some sections of the community still feel that they lack support and believe the peace process has not provided for them.

This state of mind is widespread within Northern Ireland. More people have taken their own lives there in the last 20 years than were killed during the Troubles.

Yet even in this psychologically fraught context, British politicians recklessly toy with the idea of reinstating a border and dismiss concerns with talk of technology that will ensure “frictionless” trade.

The UK bears grave responsibility for what is happening in Northern Ireland. It must govern all the people there, even those who remain unreconstructed and inconvenient.

Sinéad O’Shea is a film-maker and journalist

- Guardian