Loughinisland massacre findings offers chilling insight into the murky world of Special Branch
The Loughinisland report provides another disturbing insight into some of the darkest corners of policing in Northern Ireland and how sections of an intelligence apparatus set up to combat terrorism descended, in the Ombudsman's words, into "a corrupting involvement - tacitly, or otherwise - in serious criminal acts".
When the attack took place, the killings were initially regarded as yet another in the apparently endless series of Troubles' murders and were seen as part of a "tit-for-tat" series within that year's 69 deaths.
After members of the now-defunct INLA had driven up the Shankill Road and shot dead several UVF figures, everyone was braced for the inevitable loyalist retaliation.
The new report adds the grim specific detail that UVF leaders ordered "blood on the streets" in reprisal.
It is still unclear why the gunmen singled out for retaliation an obscure pub in a relatively peaceful area of Co Down, killing six men.
These included Barney Green, one of the oldest victims of the Troubles, who was an 87-year-old described as "a really jolly man who lived his life to the full".
Although the RUC promised to pursue the killers, no one was charged with the murders. Such a lack of convictions was not uncommon during the Troubles, but in this case, the Ombudsman was concerned by "unexplained delays in arrests, the loss of potential forensic opportunities and what might be described as inconsistencies, or anomalies".
His confident assertion that there was collusion in the incident is largely based on his study of the Special Branch's treatment of informers.
It appears that there was no specific intelligence that the Loughinisland bar would be attacked, but there was general knowledge of UVF activities in both Co Down and in Belfast.
While a high-profile murder inquiry was launched, the Ombudsman encountered many examples of failures to pass on intelligence to investigators.
This meant, he said, that there were cases where lines of inquiry were not followed and that some individuals, who could have been subject to robust investigation, were excluded from consideration.
The Ombudsman was taken aback to discover that one of those suspected of the attack was not only an RUC informant, but continued in this role for some years after the attack.
He said: "The failure to investigate adequately the role of state agents in a range of criminal activities effectively meant they were protected from serious investigation and continued in their criminal activities."
The Ombudsman also reported that the intelligence community knew of large-scale loyalist arms-smuggling by known paramilitary figures, but that only part of the consignment was seized. Ballistic records indicated that rifles from the consignment were used in the killings, or attempted murders, of at least 70 people.
All this, he concluded, combined with a flawed Loughinisland investigation, had denied justice for the victims and survivors of that attack.
Loughinisland is now added to the list of official confirmation of collusion involving security force agents within violent loyalist organisations.
The most striking of these was David Cameron's 2012 Commons statement that the death of solicitor Pat Finucane had arisen from "shocking levels of collusion".