The families of four soldiers killed in the 1982 IRA Hyde Park bombings are launching a civil case against one of the alleged bombers.
John Downey had denied involvement and a 2014 prosecution was dropped when a judge ruled an official assurance given in error meant he could not face trial.
He had an “on the run” letter telling him he was no longer a wanted man.
The Sun reports that the families thanked its readers for their support in securing legal aid for civil action.
Mr Downey, 66, denied murdering the soldiers.
He cited an official letter he had received in 2007 assuring him he would not face arrest and prosecution for IRA crimes.
At that time, Mr Justice Sweeney heard from Sinn Féin’s Gerry Kelly that 187 people had received “on the run” letters assuring them they did not face arrest and prosecution for IRA crimes.
Mr Justice Sweeney’s judgment laid bare the details of a secret arrangement to deal with several hundred republicans against whom there was no existing evidence.
They may still have been potentially of interest to police after July 2000.
The Hyde Park attack on 20 July 1982 killed Squadron Quartermaster Corporal Roy Bright, Lieutenant Anthony Daly, Trooper Simon Tipper and Lance Corporal Jeffrey Young.
Former Ulster Unionist MP, Danny Kinahan, welcomed the news.
Mr Kinahan, who was a former colleague of the soldiers who were murdered, said: “The granting of legal aid to the Hyde Park Justice Campaign is fantastic news, but it should have happened a lot sooner.
“The families of my murdered colleagues have been put through hell.
“Firstly they lost their loved ones, stolen from them in the prime of their lives.
“Then they suffered the pain of the farce of the trial of John Downey being thrown out because of one of the despicable on-the-run letters.
“And finally they have had to endure being put through the wringer by the Legal Aid Agency who repeatedly refused their application for Legal Aid.”
Mr Kinahan said he was glad that the Legal Aid Agency has reversed its previous decisions.
The Hyde Park attack is one of the most significant unsolved IRA bombings of The Troubles.
One other person was convicted in relation to the deaths before being later cleared on appeal.