TWENTY years ago this month I sat down and wrote a front page investigation for The Herald headlined: “My unit conspired in the murder of civilians in Ireland”. The date on the article is November 19, 2000. Two decades later justice has still not been done.

The article was based on the testimony of a British military intelligence officer, who told how the organisation they were part of – the army’s Force Research Unit – used double agents inside loyalist terrorist organisations as proxy assassins. Sometimes victims were IRA members, but the dead also included ordinary civilians.

My sources in British intelligence told me that knowledge of collusion went all the way to Whitehall, with information passed to the Ministry of Defence and Downing Street.

In many cases, terrorist double agents were used to kill suspects the security forces couldn’t legitimately arrest. In order to maintain their cover as paramilitaries, these double agents were allowed by their army handlers to continue terrorist operations. That meant bombing and shooting – taking the lives of civilians.

My work on collusion and the Dirty War began with the assassination of the Belfast solicitor Pat Finucane by loyalist gunmen. Finucane’s death was planned by Brian Nelson, the UDA’s intelligence officer. He was also the army’s most prized agent among loyalist terrorists. Finucane was targeted because he’d represented IRA defendants.

My investigations went on to reveal the mammoth scale of collusion and prove that the British army wasn’t just using loyalist killers as their proxies, but republican double agents too. The work culminated a number of years later revealing the identity of the British army’s most highly placed double agent inside the IRA – the spy known by the codename Stakeknife, senior republican Freddie Scappaticci.

For investigations like the ones mentioned above – and others such as ‘Exposed: Captain who aided hitmen’ – I was threatened with gagging orders and browbeaten by the Ministry of Defence. The Herald stood firm and I went on to spend years uncovering the criminal conduct of the security forces in Northern Ireland during the Troubles.

For years – as a journalist and citizen – I’ve called for public inquiries into individual murders, such as the assassination of Pat Finucane, as well as a generic inquiry into state collusion with terror organisations, and more specifically a Truth and Reconciliation Commission for Northern Ireland.

I envision such a commission adopting an approach similar to that of South Africa post-Apartheid, in which those guilty of past crimes could step forward and give an account of their actions in order to help the country heal and give victims’ families some closure. There wouldn’t need to be subsequent trials. If members of the IRA, UVF, British Army and what was the RUC told the truth, then a general amnesty could be imposed in return for honest testimony which helps close the book on the dreadful legacy of history.

Earlier this week, the British government said there’d currently be no inquiry into state collusion in Finucane’s murder – even though there’s insurmountable evidence that the UK’s security forces aided and abetted the assassination.

Canadian judge Peter Cory reviewed a number of cases involving alleged collusion in the early 2000s on behalf of the British and Irish governments and found sufficient evidence of collusion to recommend public inquiries. In 2005, however, the British government passed the Inquiries Act, limiting the scope of any official investigations proposed by Cory. The judge said this “would make a meaningful inquiry impossible”.

In 2012, then Prime Minister David Cameron admitted there’d been “shocking” levels of collusion in the Finucane killing, and apologised to the Finucane family.

Eight years later, Conservative Northern Ireland secretary Brandon Lewis this week says he wants to “allow ongoing [Northern Ireland Police] and Police Ombudsman processes to move forward”. How much longer is needed? Finucane was murdered in front of his wife and children in his own home in 1989. His widow, Geraldine, said the ruling was “yet another insult added to a deep and lasting injury”.

Some weeks before Finucane was murdered then Conservative Home Office minister Douglas Hogg said in the House of Commons there were a number of lawyers in Northern Ireland “unduly sympathetic to the IRA”.

One of the UDA gunmen who shot Finucane, Ken Barrett, later claimed a police officer told him the solicitor was in the IRA – something the Finucane family has angrily denied. “The peelers wanted him whacked,” Barrett was recorded saying. “We whacked him and that is the end of the story.”

Barrett was convicted of murder. When Brian Nelson – the army’s UDA double agent – also landed in court, a senior British army officer, Brigadier Gordon Kerr, testified on his behalf.

Kerr – an Aberdonian – was the head of the Force Research Unit, the military intelligence outfit which ran agents including Nelson and Stakeknife, and was up to its neck in the Dirty War. Kerr would go on to be the British military attaché to the UK embassy in Beijing – promoted to the highest levels for his work in Northern Ireland.

Former PSNI Chief Constable Hugh Orde has said Kerr should have been put on trial. Raymond White, former head of RUC Special Branch, says he raised the issue of collusion personally with Margaret Thatcher and his concerns were ignored. The message he got from the Tory government was “carry on – just don’t get caught”.

Collusion and the Dirty War in Northern Ireland is a cancer at the heart of British democracy. No nation can call itself a democracy if it uses – or has used – its security forces illegally against its own citizens, or to circumvent the rule of law and justice in the courts.

In the final analysis, what difference is there between the behaviour of the British state in Northern Ireland during the Troubles and that of Latin American and African dictatorships of the 1970s which unleashed death squads against their own people?

Once you understand the behaviour of the British government during the Troubles every act by the UK is tarnished. How can we dare champion human rights around the world, for instance, when our government has done what it’s done?

Remember – Britain didn’t carry out these crimes in some far off land. We did this in our own country. We murdered our own people. Until that horror is addressed, Britain is forever shamed.