The author of a royal biography on the Mountbattens has written to Garda Commissioner Drew Harris to ask for his help in uncovering secret Kincora papers.
Mr Harris is a former PSNI Deputy Chief Constable and acted as liaison with MI5, and writer Andrew Lownie believes "he would be the right man to know where the bodies are buried on either side of the Irish border".
In the letter, Lownie says that almost 40 years since the IRA assassination of Earl Mountbatten, "many important relevant files surrounding his life and death remain closed".
'Sean', a former resident of Kincora House in east Belfast, has spoken to Lownie for the biography, The Mountbattens: Their Lives And Loves.
He said he was driven from Kincora across the border with the Republic to Classiebawn, Mountbatten's castle in Sligo, in 1977.
As the men who brought him waited outside, he was taken into a darkened room where he was joined by "a man who undressed me and then gave me oral sex, I was there about an hour. He spoke quietly and tried to make me feel comfortable".
"He was one of those men who wanted attention, wanted you to chase him," he recalled.
"I think he felt some shame. He said very sadly: 'I hate these feelings'.
"He grabbed my hand and put it on his chest… I only recognised who he was when I saw on the news that Lord Mountbatten had been killed."
During his research for the biography Lownie tried to gain access to certain Irish State files including Garda files about Mountbatten, only to be turned down.
He was told that the Mountbatten case is still open and there may yet be further prosecutions.
But Lownie has now also revealed that he has information linking several unnamed prominent republicans in the Republic to Mountbatten's 1979 murder and that they are still living free in Ireland.
The only person to have served a prison sentence for the murder was Thomas McMahon.
McMahon was sentenced to life imprisonment in Dublin on November 23, 1979 but was released in 1998 under the terms of the Good Friday Agreement.
In 2017 the Historical Institutional Abuse Inquiry (HIA) concluded that abuse at the home was limited to three staff members and there was no collusion by the State or intelligence services in covering it up. The staff members were jailed in 1981.
Sir Anthony Hart, who chaired the HIA, said in his conclusions: "We are satisfied that the interest of the RUC Special Branch, of MI5, of SIS and of Army intelligence in [Kincora housemaster] William McGrath was solely because he was the commanding officer of Tara [a loyalist paramilitary organisation]."
The report continued: "Those investigations did not find, and our inquiry has not found, any credible evidence to show that there is any basis for the allegations that have been made over the years about the involvement of others in sexual abuse of residents in Kincora, or anything to show that the security agencies were complicit in any form of exploitation of sexual abuse in Kincora for any purpose."
There are about 20 files on Kincora from the 1980s which should be in the National Archives under the 20-year rule. Some are still "temporarily retained", while others were due for consideration in 2018 after the Hart Inquiry sat.
Lownie was first told that they would be deposited in 2018, then that they would be in the National Archives by this summer.
"Yet just last week I was told by the Northern Ireland Press section that they need to be reviewed by the advisory council to the National Archives, the first time it has been mentioned," he said.
In 1990 writer Robin (Ribert Harbinson) Bryans, who died in 2005, disclosed that Lord Mountbatten, Anthony Blunt and others were part of a London-based group that held all-male 'parties' in Blessingbourne House, Fivemiletown, Co Tyrone, when it was owned by Captain Peter Montgomery, a cousin of Field Marshal Montgomery of WWII fame. Leslie Mackie, of Mackie's Engineering, was another frequent visitor.
Montgomery is believed to have trafficked boys from Portora Royal School to these parties for paedophiles.
Ironically, Sir Anthony Hart, who chaired the HIA, was himself a Portora old boy.
John McKeague, a founding member of the loyalist terrorist Red Hand Commando, was another frequent visitor to Kincora.
By 1968 he had already been questioned in relation to a sexual assault on two young boys. The charges were dropped after the intervention of some 'friends' who held prominent positions in Northern Ireland society.
In January 1982 McKeague was interviewed by detectives investigating Kincora about his involvement in the sexual abuse. Fearful of returning to prison, McKeague told friends that he was prepared to name others involved in the paedophile ring to avoid a sentence.
Just a short time later, on January 29, 1982, McKeague was shot dead by two gunmen from the INLA in his shop on the Albertbridge Road, east Belfast. According to some sources, one of the gunmen was an RUC Special Branch agent, while the other was said to have military intelligence links.
The late DUP leader Ian Paisley, former MP for North Antrim, was accused of failing to report McGrath's abuse to the relevant authorities. He initially denied ever being advised by his informant Valerie Shaw, a member of the Free Presbyterian Church which Paisley founded, that it was taking place.
RUC officers probing the Kincora allegations after the suicide of a former resident later interviewed a number of politicians in Northern Ireland, including Rev Paisley.
Investigating officers even had to ask Paisley if he was a homosexual.
In The Kincora Scandal, Chris Moore claims that an Army intelligence officer, who he calls 'James', told his superiors as far back as 1975 of the allegations against McGrath.
But MI5, which ran McGrath as an agent so that he could enable them to destabilise Northern Ireland in the event of a British withdrawal, ordered him to drop the investigation. McGrath was eventually jailed in 1981, along with wardens Joseph Mains and Raymond Semple, after admitting ritually abusing boys in care.
'James' also gave evidence to the Bloody Sunday Inquiry as 'Observer B'. He had been an MI5 informant in Derry at the time of the shootings.
He was also a former Army sergeant major, an Englishman married to a Northern Ireland woman. He died in 2003 shortly after giving evidence to Lord Saville.
Liam Clarke, former political editor of the Belfast Telegraph, spoke to him in 1987 about his efforts to alert the authorities to Kincora before his handlers made his financial problems disappear to shut him up.
"My case officer told me to leave McGrath to them and I have always believed they used the information [about his sexual activities] to recruit him as an informer," Observer B told Mr Clarke.
Observer B was talking about William McGrath, the housemaster of Kincora Boys' Home and one of three men later jailed for abusing youngsters in his care. Observer B, who had supplied a dossier to MI5, was promptly told to leave McGrath's Tara group and join the UDA.
The late Peter McKenna was the first journalist to reveal the secrets of Kincora and its shadowy spymasters in the Irish Independent in 1980.
The matter was raised at Westminster by MP Gerry (later Baron) Fitt, who was "shocked to the core" by the reports.
When she announced the establishment of the HIA, Northern Ireland Secretary Theresa Villiers MP said that all State agencies would co-operate with the inquiry. But last night Andrew Lownie lashed out at Government promises and assurances.
"The Kincora files are being withheld using every trick in the book. It is a can of worms being kicked into touch," he said.
Lownie - a trustee of the Campaign for Freedom of Information - added: "My view is that we need to be open about our history and give full and open disclosure about the past so that we can start to make amends to the victims as Sir Anthony Hart recommended."
Dear Mr Harris,
I am a British historian researching the life of Earl Mountbatten. I am concerned that almost 40 years since his death many important relevant files surrounding his life and death remain closed.
The Northern Ireland Office and Cabinet Office were due to release almost 30 files on Kincora to the National Archives last year under their statutory obligations but that has not taken place. I hope the Garda are prepared to be more open and transparent.
I am writing to ask if the files concerning his murder can now be made available, given it is clear the case is closed.
Will you also make public the Garda security logs, so it can be established who visited Mountbatten’s home Classiebawn in the Republic in the 1970s, together with details of any car registrations in the general vicinity of Classiebawn which the Garda noted.
I am happy to fly to Dublin for a meeting.