For almost 40 years after Mr McGreanery was shot dead by a British soldier on the streets of Londonderry, his memory has been sullied by allegations that he was carrying a weapon, that he was attempting to fire on the security services and even that he was a member of a paramilitary group.
Mr McGreanery, who was 41 when he died, has finally been exonerated. A new report that shows that he was simply an innocent civilian who was cut down in what police at the time viewed as nothing less than cold-blooded murder. He was not a victim of Bloody Sunday, yet his death on 15 September 1971 could hold the key to the actions of British soldiers four months later.
An official report into the circumstances of his death, released this month and obtained by
The Independent on Sunday, shows how the Government's response to the shooting helped to pave the way for the Bogside assault on 30 January 1972 – in effect, giving the green light to soldiers to act with impunity.
The report, from the Police Service of Northern Ireland's Historical Enquiries Team (HET), reveals how the chief of what was then the Royal Ulster Constabulary (RUC) in Londonderry recommended that the soldier who fired the fatal shot be prosecuted for murder. But this was overruled in December 1971 by the province's attorney-general, Basil Kelly, who rejected any prosecution on the basis that the soldier was "acting in the course of his duty".
Mr McGreanery was shot dead by a member of the Grenadier Guards during a period of heightened tensions in the city. For decades, his memory was tarnished by allegations that he was an armed terrorist attempting to fire on the security services.
Like the Bloody Sunday victims, he has finally been absolved of any blame. "He was not involved with any paramilitary organisation; he was not carrying a firearm of any description, and he posed no threat to the soldiers at the observation post," the report says.
The revelations confirm long-held suspicions that soldiers "would be protected as far as the prosecution authorities were concerned", according to Mark Durkan, SDLP MP for Foyle. He added that the case meant that the British Army was effectively "being told they would be immune from prosecution, and whatever they did they could do with impunity".
Paul O'Connell of the Pat Finucane Centre, a human rights organisation, said: "If the authorities had agreed to the RUC's position and started proceedings against a British soldier, then all local military commanders would have been told to act with greater control." Instead, six weeks after British soldiers had effectively been given the signal that they could expect immunity from prosecution, they shot 27 civilians on Bloody Sunday.
The jubilation at last week's publication of the Saville report, prompted by a heartfelt apology from the Prime Minister, David Cameron, for the "unjustified and unjustifiable" killing of 13 people on Bloody Sunday, marked the end of the road for those families who had waited half a lifetime for their loved ones to be exonerated. But the shockwaves set off by the detail in thousands of pages of the Saville report continue to radiate outwards, prompting calls for perjury prosecutions and for further inquiries into other cases where British soldiers killed civilians, such as the Ballymurphy massacre in Belfast in August 1971, when 11 civilians were shot.
Sir Alasdair Fraser, Director of Public Prosecutions for Northern Ireland, will meet Northern Ireland's new Chief Constable, Matt Baggott, tomorrow to discuss how police investigations might help future prosecutions.
And while the victims of Bloody Sunday have been exonerated, the report has not made comfortable reading for republicans – with its revelation that former IRA chief Martin McGuinness, now Deputy First Minister of Northern Ireland, was carrying a submachine gun that day. "We cannot eliminate the possibility that he fired this weapon after the soldiers had come into the Bogside," the report states.
It adds that the same gun may have been used to kill two policemen in Londonderry two days before Bloody Sunday.
In an attempt to prevent the report from opening up old wounds, Mr Cameron has made a full apology and Mr McGuinness has not led calls for prosecutions. But while Lord Saville's conclusions may have closed the chapter on Bloody Sunday, it is far from ending the story of the atrocities – on all sides – that dominated the Troubles.
A unique insight into the mindset of soldiers on the eve of Bloody Sunday is revealed in an unpublished extract of a book by an officer who served that day. The identity of the author has never been established, but his account was submitted from the Parachute Regiment to the MoD for clearance in the 1970s, only to emerge as new evidence at the Saville inquiry.
It recalls the frustration of dealing with protesters at a march at Dungannon the day before Bloody Sunday: "It was almost as though we were willing them to come out fighting, and bring the whole business down to a level which we could at last understand and appreciate – violence."
And the officer tells how morale was high on 30 January, "after briefing on the promised confrontation – which they were all looking forward to" and "the expectations of 'preparation for battle' kept out the chill of the bright winter morning we had woken up to... This time the 'enemy' had promised us the biggest and best civil rights march... And we would be ready for them – indeed, this was an opportunity we had been waiting for. We, at last, had plans of our own".
The author cites fears that the "plan" was "fraught with danger" of becoming a "GMFU" (grand military fuck-up), and recalls how one officer's wife, on being told of the plans, remarked: "I can just see the headlines – Londonderry's Sharpville."