A damages claim by families of the Hyde Park bombing victims against a suspect has reached the High Court.
Relatives of the four Royal Household Cavalrymen who died in the July 1982 blast are bringing a civil action against John Downey.
Squadron Quartermaster Corporal Roy Bright, 36, Lieutenant Dennis Daly, 23, Trooper Simon Tipper, 19, and Lance Corporal Jeffrey Young, 19, were killed by a car bomb as they rode through the central London park to attend the changing of the guard.
Convicted IRA member Mr Downey - who has always denied any involvement in the attack - was charged four years ago with the murders, but the prosecution at the Old Bailey collapsed in 2014.
Family members of those killed launched legal action against Mr Downey after the collapse of the trial, and the first hearing in the case is due to take place in London on Tuesday.
They initially asked for help with legal fees through crowdfunding after being refused legal aid five times, but The Sun revealed in February that they have been granted public funding to pursue the case.
Speaking at that time, a Legal Aid Agency spokesman confirmed the award of legal aid and said: “Our deepest sympathies remain with those affected by this atrocity.”
The car bomb left in South Carriage Drive killed the four soldiers and injured others as they travelled from their barracks to Buckingham Palace.
Seven horses were also killed and another horse, Sefton, survived terrible injuries.
The criminal case against Mr Downey, from Co Donegal, dramatically collapsed after it was revealed he had received a written assurance from former prime minister Tony Blair’s government that he was no longer wanted.
The letter was issued under the terms of the controversial On The Runs (OTRs) Scheme.
Trial judge Mr Justice Sweeney ruled that Downey’s arrest at Gatwick Airport, as he passed through the UK on the way to a holiday, represented an abuse of process and he put a stay on any future prosecution.