Lawyers have applied to a coroner to reopen the inquests of victims of the 1974 Guildford pub bombings.
Five died and 65 were injured in the IRA blasts but those responsible were never prosecuted and the inquests never concluded.
The wrongfully-convicted Guildford Four served 15 years before release.
KRW Law said its clients and families of the victims needed the truth. The Surrey coroner said the application would be dealt with in due course.
The law firm is representing a former soldier who survived the blast at the Horse & Groom and is still suffering from PTSD, and Ann McKernan, sister of wrongly-jailed Gerry Conlon who died in 2014.
'Put through hell'
Mrs McKernan said: "Justice has no sell-by date."
She said her mother was "put through hell for 15 years" and she said the families of the victims were also "going through the same hell".
"Believe me, when I think of my family, I also think of them," she said.
Soldiers Ann Hamilton, 19, Caroline Slater, 18, William Forsyth, 18, and John Hunter, 17, and plasterer Paul Craig, 21, all died in the blast at the Horse & Groom on 5 October 1974.
The BBC has been in contact with the victims' families and friends, but most remain too traumatised to talk publicly.
After viewing inquest papers from the time, lawyers said there was no record of the original hearings being resumed.
Files obtained by BBC
A legal submission by KRW Law to Surrey Coroner Richard Travers said for many years the focus had been on the Guildford Four's miscarriage of justice.
It said victims' families had "never been permitted" an opportunity to testify and were "merely bystanders" at the original trial and appeals.
The firm claimed questions remained over the actions of police and lawyers at the time - including the original police investigation, alleged changes to evidence by prosecutors, and the police response after the IRA's Balcombe Street unit admitted in 1976 it had planted the bombs.
The legal bid cites memos and papers obtained by the BBC at the National Archives over the past year and also raises the question why many official files relating to the Guildford Four remain closed.
The submission concluded: "There remains a profound belief that justice has not been done."
A spokeswoman for the Surrey coroner's office said: "I can confirm that an application has been received at the court from KRW Law to resume the inquests into the deaths of the victims of the Guildford Pub Bombings 1974.
"The coroner will be dealing with this in due course and it will be given all proper consideration."
KRW Law also pointed to the "large number" of fresh inquests in Ireland relating to the Northern Ireland conflict.
It claims had the Guildford bombings happened there, it was more likely the deaths would have been subject to further investigation.
The submission said: "It appears unfair to provide comprehensive public investigations into these tragic deaths and yet fail to do so for the families of the victims in Guildford."
The Guildford Four
- 5 October 1974 - IRA bombs explode in two pubs in Guildford, Surrey, killing five people and injuring scores more. Guildford was known as a "garrison town", with several barracks nearby, at Stoughton and Pirbright and Aldershot in Hampshire, and a nightlife that was popular with the 6,000 military personnel in the area
- 22 October 1975 - Paul Hill, Gerry Conlon, Patrick Armstrong and Carole Richardson - the Guildford Four - jailed for life at the Old Bailey
- 19 October 1989 - After years of campaigning, the Court of Appeal quashes the convictions, ruling them as unsafe, and releases them
- 9 February 2005 - Prime Minister Tony Blair formally apologises to the Guildford Four for the miscarriage of justice they suffered
This month, KRW Law called on the Attorney General to launch a fresh probe into the original Surrey Police investigation and the original prosecution of the Guildford Four.
A spokeswoman for the Attorney General's Office said: "We have received the application and will consider it carefully."
Surrey Police said it was awaiting any decisions by the Attorney General.
The force also said it was aware of the application to the coroner. A spokeswoman said: "We will wait to hear as to any decisions made by the coroner following this representation, and any subsequent direction made."
The law firm is also representing the families of victims of the 1974 pub bombings in Birmingham, where 21 people died and inquests have reopened.
It said there are obvious parallels between the Guildford and Birmingham cases.