The jury hearing inquests into the deaths of the 21 people killed in the 1974 IRA Birmingham pub bombings has retired to consider its conclusions.

The 11 members of the panel have sat through almost six weeks of evidence and have been tasked with completing a questionnaire, listing their narrative findings.

Two massive explosions caused what one witness described as “pure carnage”, ripping apart the packed Tavern in the Town and Mulberry Bush pubs on the night of November 21, killing 21 people and injuring 220 others.

Birmingham pub bombings inquest
Debris and damaged shopfronts by the entrance to the basement Tavern in the Town pub (PA)

A third bomb planted at Barclays Bank in Hagley Road, a mile away, failed to go off.

Before sending the jury out, coroner Sir Peter Thornton QC directed jurors to find that the victims were “unlawfully killed”.

Jurors must also answer specific questions, including about the adequacy of the coded bomb warning given by the attackers, the police’s response to the call, and whether the authorities were tipped off about the bombings.

Sir Peter spent all of Wednesday and part of Thursday summing up evidence which has included testimony from a convicted ex-IRA bomber, the police on duty that night, rescuers, and survivors.

He paid tribute to the “many who were very brave volunteers that night” helping the emergency services.

Birmingham pub bombings inquest
The Mulberry Bush bomb killed 10 people (PA)

There was a dramatic twist towards the end of evidence at the hearings, when a former IRA member named four of the men he claimed were involved in the bombings as Seamus McLoughlin, Mick Murray, Michael Hayes and James Francis Gavin.

The man, identified in court only as “Witness O”, said he had been authorised to give those names by the current head of the IRA in Dublin.

Murray, who died in 1999, is said to have called in the bomb warning at 8.11pm to newspaper telephonist Ian Cropper, giving the code word “Double X”.

However, jurors heard that the warning had only given the locations as the landmark Rotunda building and the nearby Tax Office in New Street, making no mention of pubs.

In his evidence to the inquests, the then IRA head of intelligence in Ireland, Kieran Conway, described the victims’ deaths as “accidental”, in an “IRA operation that went badly wrong”.

Former MP Chris Mullin was also called a “disgrace” by Julie Hambleton, the sister of one victim, when he refused to name any of the still-living bombers during his evidence.

Birmingham pub bombings inquest
The massive explosion in the basement Tavern in the Town blew out the floor above, and killed 11 people (PA)

The hearings have been held as Article 2 inquests, examining whether the British State or its agents failed to adequately protect the victims.

Jurors heard that Birmingham city centre had been “denuded” of police after officers were pulled away to bolster security for IRA bomber James McDade’s funeral procession in Coventry.

Responding to the warning call, officers sent to the Rotunda made no attempts to evacuate the Mulberry Bush, located in the base of the famous building, or set up an area cordon, the jury was told.

It also emerged from officers’ testimony that police responding to such bomb threats were not routinely told if the warnings had been called in with agreed IRA codewords.

The inquests heard evidence of possible forewarnings of the bombings, including a conversation about a forthcoming attack between IRA inmates allegedly overheard in prison, and another in a pub where a customer heard men with Irish accents discussing “bangs”.

Ex-IRA man Witness O also claimed that, while still a prisoner, he told to detectives, a day or after the bombings, that McLoughlin had planned the attacks, but heard nothing more. McLoughlin died in 2014.

Jurors have heard that key evidence is missing or was never collected.

Birmingham pub bombing inquest
Coroner Sir Peter Thornton QC (right) took jurors to the scene of both bombs, at the start of the inquests (Richard Vernalls/PA)

The third unexploded bomb has been misplaced and West Midlands Police’s force control room call tapes from the night were recorded over.

Only limited written records still exist of the police’s response on the night, including just three 999 logs, despite witness statements referring to “numerous” calls being made.

CCTV from the lobby of the Rotunda, which may have shown the bombers passing by, was never collected or even viewed by police, according to evidence from the former building manager.

The inquests, which are being held at the civil courts building in Birmingham, came about after years of campaigning by relatives of the dead for a full account into the circumstances of what happened that night.

The pub bombings were the deadliest post-Second World War attack on the British mainland, until the 7/7 London terrorist attacks in 2005.

A botched investigation by West Midlands Police led to the 1975 convictions of the Birmingham Six, but their convictions were quashed by the Court of Appeal in 1991.

Opening the inquests in February, Sir Peter, the former chief coroner for England and Wales, said: “These were calamitous events and require full and fair investigation at least as far as the inquest procedures may permit, under law.”

Julie Hambleton, who lost her older sister in the bombings, said before the hearings that bereaved families wanted “truth, justice and accountability”.