That question remains: could there have been a better outcome to the siege – would the lives of cafe manager Tori Johnson and barrister Katrina Dawson have been saved – if police had stormed the cafe at a time of their own choosing instead of waiting until after the execution of a hostage?

In technical jargon, that comes down to a choice between a "deliberate action" (a DA) as opposed to an emergency action (an EA). The inquiry has heard that tactical police advisers had drawn up a DA and were keen for it to be at least approved, for them to hold in reserve as an option. But senior commanders up the chain did not want to approve the plan.

Among other reasons, they feared large loss of life because of a belief that gunman Man Haron Monis also had a bomb. But was there another reason for police caution? That they were wary about taking the initiative for fear of an adverse public reaction should things go wrong? Under sustained questioning on this point, Mr Scipione stood his ground. This had not been driving him on the night, he said.

He also stressed, repeatedly – as did deputy Catherine Burn before him – that he did not have an operational role during the siege, and that under the protocols applying on the night operational decisions would be made by the commanders at the forward police post and at the police operations centre.

Why then did a police scribe record a conversation between police commander Mark Jenkins and Mr Scipione at 10.57pm on the night of the siege to the effect that a "DA plan [would] occur as a last resort – COP"? (COP being the acronym for Commissioner of Police.)

But Mr Scipione vehemently denies issuing any such instruction or offering any such advice. Neither he nor Mr Jenkins have been able to shed plain light on how the subject of a DA came up. Mr Scipione insists his call to Mr Jenkins was a "welfare check" to see if his commander had everything he needed.

He also rejected any suggestion from counsel assisting the inquiry, Jeremy Gormly, that an email he sent earlier that evening about taking down a hostage video from YouTube would have been construed as a direction. He said he raised the issue with police commanders in the context of an operation planned for the next day, aiming to damp down the risk of violent retaliations in response to the siege. But the discretion remained theirs, he insisted.

No matter how many times Mr Gormly came at this issue, Mr Scipione stood his ground, as he did on the DA versus EA issue. "A DA was an option among a range of options", he said. "Whether it could have brought this under control or made it worse, we will never know." Nor will it ever be known if it could have made the situation better.

Mr Scipione told the inquest that "in terms of the buck, it stopped with me." But he has also been at considerable pains to distance himself from the key calls that frontline police commanders made that night. It is a fine balance to try to strike. Mr Scipione is a public official of exceptional adroitness. And that was on full display during his near five-hour turn in the witness box on Wednesday.