The inquest into the deaths of five people killed in the 1974 Guildford pub bombings will be resumed.
Four soldiers and a plasterer were killed and 65 others were injured when the IRA blew up two pubs in the Surrey town.
The Guildford Four were wrongly convicted and jailed for 15 years, before being released in 1989.
Coroner Richard Travers said: "This case is not of such antiquity that it should be considered ancient history."
Handing down his decision at Woking Coroner's Court, Mr Travers said some witnesses had died which presented "serious challenges".
But he said the clientele in the pubs were young at the time and would be now in their 60s and 70s.
No date has yet been set for the inquest to resume and a pre-inquest review will be held at a later date.
Soldiers Ann Hamilton, 19, Caroline Slater, 18, William Forsyth, 18, and John Hunter, 17, as well as plasterer Paul Craig, 21, died following the first blast at the Horse and Groom on 5 October 1974.
Another bomb at a second pub also exploded but no-one died.
Paul Hill, Gerry Conlon, Patrick Armstrong and Carole Richardson - known as the Guildford Four - were wrongly convicted of the attacks in what is considered one of Britain's biggest miscarriages of justice.
In a statement following the coroner's ruling, Surrey Police said they had already begun cataloguing all material held in relation to the bombings, but that it would take up to a further 18 months to complete.
The original inquest proceedings were suspended when the Guildford Four were convicted in 1975.
Mr Travers said the attacks "still matter" to the people who died and the people of Guildford and added that "the deceased, the families and the public are entitled to hear matters formally in open court".
The coroner said the hearing would seek to examine details such as the location and precise time of the blast, who was with the victims at the time, whether the victims died immediately and the response of the emergency services.
But he said the resumed inquest would not have the scope to explore who was responsible for the bomb, the composition of the explosive device or any claims police lied during the trial of the Guildford Four.
KRW Law, who represent the family of Ms Hamilton and survivor Yvonne Tagg, made an application to resume the inquests after the BBC obtained papers about the case, and coroner's archives showed the original proceedings never concluded.
Spokesman Christopher Stanley said he believed his clients would be "happy" at the outcome.
"This is the first and last opportunity for our clients to have a full investigation," he said.
Richard O'Rawe, a childhood friend of Gerry Conlon, said he would have been delighted.
He said Mr Conlon, who died in 2014, struggled to get justice all his life and now "we will get to the truth".
A four-man IRA unit known as the "Balcombe Street gang" claimed responsibility for the attacks in 1976 but were not charged.
Over the years it has been disputed how many members were in the unit - a court transcript suggested up to 20.
Seven people, known as the Maguire Seven, were jailed on explosive charges over the attacks but they also had their convictions quashed.