The Whiskey Au Go Go nightclub fire, in March 1973, was Australia's worst mass murder until the 1996 Port Arthur massacre.

Londoner Finch and John Andrew Stuart, originally from the Gold Coast, were convicted in October 1973 of the murder of 17-year-old waitress Jenny Denise Davie, who died in the fire at the nightclub, in a building that still stands in Amelia Street in Fortitude Valley.

Stuart died in prison in January 1979 and was buried in Lutwyche cemetery but Finch was granted parole in 1988 and deported to England after serving 15 years in Boggo Road Gaol.

Later that year, Finch admitted he, Stuart and others burned down the Whiskey Au Go Go but changed his story when told he could be extradited.

In June 2017, Queensland Attorney-General Yvette D'Ath ordered a new coronial inquest into the 15 deaths, after Vincent O'Dempsey and Garry Dubois were convicted of murdering Highgate Hill's Barbara McCulkin and her two daughters,  Vicki, 13, and Leanne, 11.

On trial last year, O'Dempsey denied police allegations he had murdered Ms McCulkin because she was nervous and wanted to talk about a series of Brisbane nightclub fires, including the Whiskey Au Go Go blaze.

When he sentenced O'Dempsey and Dubois in June 2017, Justice Peter Applegarth told the court there was evidence O'Dempsey was concerned by reports "in the late 1990s" that Finch might return to Brisbane.

News Corp tracked down Finch, now 74,  at his home in Basildon, Essex, west of London, where he repeated his long-held denial to ever confessing to police about the Whiskey Au Go Go fire-bombings.

The convicted killer offered to take a lie detector test to prove he never confessed to police.

The police commissioner now wants Finch to return to Brisbane to answer questions.

"I think that is a very, very good step in the right direction," Mr Stewart said on Sunday.

"Who comes back to Queensland and who gives evidence will be a matter for those individuals and for the coroner.

"But I am sure that the coroner would be very interested in anything Mr Finch has to say."

Queensland Attorney-General Yvette D'Ath said she could not force Finch back to Queensland to answer questions but the coroner eventually selected to run the inquest could.

"Mr Finch is not wanted on any criminal charges in Queensland so extradition proceedings are not warranted in this case," Ms D'Ath said.

"How the inquest is conducted is a matter entirely for the coroner as an independent judicial officer."

Mr Stewart said the Queensland coroner could request terms of reference for the inquest that meant Finch could be returned to Queensland.

"The State Coroner - and the coroners around the state - have very wide and very powerful processes that they can use to demand and to direct people to answer questions," he said.

"It is a very, very powerful tribunal, but again it will be up to the coroner as to whether they use those powers.

"It will be up to how the coronial inquest is framed."

Meanwhile, experienced defence researcher Geoff Plunkett, who spent five years up to 2017 methodically going through all the original police notes into the Whiskey Au Go Go investigation, said his research indicated others were involved.

His book, The Whiskey Au Go Go Massacre: Murder, Arson and the Crime of the Century, includes references to hundreds of letters, dozens of police notes and the actual record of interview where Finch alleges he was verballed.

Mr Plunkett said the complete Whiskey Au Go Go story had not been told.

"I'm doing this for the 15 who died. I'm doing it for them basically," he said.

Mr Plunkett said he became worried when he revealed anomalies after reviewing the information from police detectives.

"I was expecting a closed case that has gone through a committal hearing, gone through a High Court hearing, seven appeals up to the Privy Council, and it had gone through internal inquiries including Operation Graveyard where they re-interviewed the detectives," he said.

"The story was always the same. Jim Finch and John Stuart done it and no one else was responsible," he said.

"So it obviously startled me when I looked at the detectives' evidence to find that there were anomalies.

"And I came to conclude that they were under enormous pressure to come up with a result straight away because John Stuart had told a reporter that an empty club - Torino's - would be firebombed first, followed by a full one, the Whiskey."