Her brother, Paratrooper Thomas Vance, was one of the 18 soldiers killed that day.
August 27th 1979 was the day the IRA struck at the heart of the Royal family and Crown forces.
That morning the Queen's cousin Lord Mountbatten, his grandson, his daughter's mother-in-law and a local boy were killed when they set off for a day's fishing off Mullaghmore in Co Sligo.
Hours later 18 soldiers - 16 of them paratroopers - lay dead in a carefully planned operation at Narrow Water.
The geography was perfect for an ambush - Narrow Water is in Northern Ireland but across the estuary was the south - where the bombs were detonated.
The first one exploded at 4.40pm, the second 25 minutes later at the castle's gatehouse where soldiers sought cover after the first blast.
Two republicans were arrested by gardai shortly after the second blast - and questioned.
Brendan Burns, 21, from Crossmaglen and Joseph Anthony Brennan, 21 from Crossmaglen.
Burns later blew himself up in 1988. Brennan was jailed for an IRA mortar attack near the border in 1995 and was freed under the Good Friday Agreement.
When they were arrested in 1979 - both gave false names and false addresses to gardai.
But they strenuously denied any involvement in Narrow Water. As they were being detained, hand swabs were taken and tests were carried out on their clothing.
It's believed the bombers lay in undergrowth. Leaves were found on the lining of Burns's anorak and in Brennan's coat pocked, also in his underwear.
A cigarette butt discovered at a look-out site was also analysed.
We have obtained a copy of the forensic report to gardai.
This is what it says: "The essence of the report is that firearms residues and ammonium nitrate are on Burns and Brennan.
"The ferns in their clothing could have come from the look out sites. A cigarette end of the type of one of the men smokes was at a lookout site and this carried saliva of Group O and the men are of Group O."
But for gardai, traces of explosives and firearms residue was not enough to prosecute for murder. Burns and Brennan were released charged only with motoring offences.
North of the border police were furious.
An undated RUC report back in 1979 details the force's clear frustration with what happened.
It said: "In spite of requests by us we were not permitted facilities to interview the suspects nor would Garda re-interview Brennan and Burns for us, using their equivalent of our crime squad."
Kevin Sheehy was on the team tasked with catching those responsible.
"I worked on that for four months and in our hearts every day when we went into work we believed had there been full co-operation there would have been successful prosecutions,'' he said.
A detective chief inspector went further in a review of the case one year after the atrocity - and strongly hinted politics was a factor.
"It is unfortunately true that the republic is a haven for terrorists on the run after the commission of outrages in Northern Ireland, such is the case in point.
"Like so many similar incidents in the past progress in this investigation can only be made on the apprehension of both Brennan and Burns and their subsequent conviction in a court of law,'' he said in his report.
The Smithwick Tribunal recently heard evidence from a former police officer only known as Witness 68 who claimed the then Taoiseach viewed the Narrow Water attack as a political crime and told gardai not to co-operate with the RUC.
But the belief that politics was a factor was spelt out in black and white - and logged in police files long before Smithwick.
"I do not think there was ever a time where political considerations were not to the fore in many of the events that were unfolding throughout what we have taken to calling the Troubles and I think that the Narrow water incident throws that up into the sharpest relief of all because of the magnitude of the event," said solicitor John McBurney.
There were two investigations into the Narrow Water atrocity.
The second one came in 1994.
The political landscape was shifting and the IRA had declared a ceasefire.
But Joe Brennan, who was the republican arrested by gardai all those years ago was back in Northern Ireland in jail awaiting trial for an IRA attack near the border - which he was later convicted of.
Police decided to re-open the Narrow Water investigation.
This time they had the full co-operation of the Garda - who were willing to testify in a Northern Ireland court.
Detective Chief Inspector Alan Mains was in charge of the new investigation.
And he recommended Joe Brennan be prosecuted for the murders of those 18 soldiers.
What came next was a blow.
The Director of Public prosecutions said no - the evidence wasn't there to provide a reasonable prospect of conviction against Brennan.
I asked Alan Mains was he convinced there was enough to prosecute?
He replied: "I have absolutely not doubt about that."
"I got the impression that here we have the alleged perpetrator already in jail for a terrorist offence. What are we going to prove?'' he added.
To this day police here believe Narrow Water could have been solved by now.
"I am satisfied that perhaps for political considerations these 18 soldiers killed at Narrow Water Castle did not get the justice from anyone, north or south?"
All of this has come as a complete shock to the family of Thomas Vance.
His sister Linda told us: "If there is somebody to be brought to justice I think that should happen. If I go out and do something I would expect to be brought to book.
"We deserve justice and closure for him."