Louise Hunt, the senior coroner for Birmingham and Solihull, will give her ruling in connection with the twin 1974 blasts on Wednesday, after already holding several review hearings.
During those hearings, families of some of those killed have put forward a central claim that the British security services had knowledge of the attacks before they were carried out.
Speaking ahead of any decision, Julie Hambleton, the leader of the Justice4the21 campaign which has called for new inquests, said: “All we want is the truth.”
Her older sister, Maxine Hambleton, then 18, was one of the victims of a blast which ripped through the underground Tavern in the Town pub, minutes after a bomb destroyed the nearby Mulberry Bush at the base of the city centre Rotunda.
The bombings, which injured 182 people, are widely accepted to have been the work of the Provisional IRA, with the terrorist group’s former intelligence director, Kieran Conway, recently describing the attacks as “an absolute disaster”.
A third bomb found in a bag in Hagley Road in Edgbaston, Birmingham, only partially detonated and its remains were later lost by West Midlands Police.
A botched investigation by the force led to the Birmingham Six being wrongly jailed for the crime.
However, the men were freed in 1991 after their convictions were ruled unsafe by the Court of Appeal.
One of their number, Paddy Joe Hill, is expected to attend the hearing after backing campaigners’ calls for new inquests.
In the 1970s, hearings were opened after the attacks; however, the process was overtaken by the criminal inquiry and the later convictions of the Birmingham Six, so the inquests were never resumed.
Ms Hambleton claimed that the botched criminal inquiry had left the victims’ relatives without knowledge of even basic facts surrounding the deadly events of November 21 1974.
She said: “Why can we not have what other families have?
“If anyone is killed in suspicious circumstances they have a right to an inquest, and the coroner then makes the judgment on how they came by their deaths.”
The review hearings, which began in February, have been attended by victims’ relatives and also barristers on behalf of the West Midlands Ambulance Service, the Police Federation and West Midlands Police.
At the last such hearing in May, Ms Hunt revealed she had received a “significant” piece of new information.
The coroner would not disclose the source but said the information related to the claim that British security services may have had knowledge of the bombings beforehand.
Speaking at the hearing on May 12, Jeremy Johnson QC, on behalf of the police force, said: “We have no principal objection to you resuming these inquests but we do say, having regard to the material you have, it has not been shown it’s appropriate to resume.”
He added there was “no evidential basis” for the allegation that the police or security services had any prior warning of the bombings.
Relatives of those killed have also indicated they would like the inquests to hear evidence about the response of all the emergency services that night.
Ahead of Wednesday, Ms Hambleton said whatever the coroner’s ruling she expected a lengthy fight for answers to questions she and other victims’ families still have for the authorities, including the British Government.
“Obviously we hope that she (the coroner) decides in our favour,” she said.
“It’s already been a long journey.
“Whichever way it goes, it will continue to be a long struggle.
“All we want is the truth.”