Any mistakes found to have been made by police or the security services will not be kept secret to spare their 'embarrassment', families bereaved in the Manchester Arena bombing have been told.
Sir John Saunders, chairman of the ongoing public inquiry into the atrocity, made the comments at a preliminary hearing today which considered 'closed hearings' and 'restriction orders' relating to certain planned witnesses.
Lawyers for the families asked for 'maximum exposure' - the inquiry will shortly move to consider the issue of whether the security services and counter-terror police could, or should, have prevented suicide bomber Salman Abedi and his brother, Hashem, from launching the plot which led to the deaths of 22 people.
Some evidence will be examined in 'closed' sessions, without the families, their counsel or the press present, after Sir John ruled that if it was heard in public, it could compromise national security or assist terrorists.
It's proposed that several witnesses will give evidence anonymously, with only limited, pre-vetted information made public afterwards.
They include counter-terror police officers, a witness for MI5 and an expert witness, witness Z – a former MI5 officer who will give their opinion on the performance of the security services.
John Cooper QC, representing a number of families, said he did not disagree with the position of closed hearings, but called for 'maximum disclosure' where possible to ensure national security wasn't used as a blanket measure to restrict public knowledge of mistakes.
He added: "National security and covering up embarrassments… you are very aware of that potentially here.
"It is something some of us have seen in other spheres, in inquests relating to deaths in the military, that sometimes, something that's called national security, we argue against redaction, we succeed, and we actually see the redaction, and it's nothing more than potentially simply an embarrassing piece of material."
Responding to him, Sir John said openness was a 'central pillar of any judicial system' and keeping evidence 'closed' must only occur when it is 'absolutely necessary'.
The chairman said he would not allow the security services to 'cover up mistakes in order to avoid embarrassment'.
But he said he would seek to do 'everything I can to not disclose things that could result in other people going through the sort of torment that the families in this case have gone through'.
"That's the balance on both sides," he said.
Sir John said he understood the desire of families to know 'absolutely everything they can know'.
But he added: "I know that the last thing that any of them want is for anything to happen in this inquiry which would lead to...which would make it easier for something like this to ever happen again."
The inquiry has been hearing harrowing evidence in relation to victims after the detonation.
Sir John told the hearing: "Mr Cooper, I hope as further reassurance to the families, you and I over the last two weeks have heard some of the most heart-rending evidence I have ever heard in any sort of tribunal.
"And we have all been affected deeply by it, and the idea I would allow the security service to cover up mistakes in order to avoid embarrassment is something, I can assure you, I would not have done even if I hadn’t heard the heart-rending evidence, but I'm even more determined.
"Equally, I would also seek to do everything I could to not disclose things that would result in other people going through the sort of torment that the families in this case have gone through."
MI5 admitted last year, in an opening statement to the inquiry, that suicide bomber Salman Abedi, 22, had come across its radar 18 times in the seven years before the May 2017 attack.
He had also been made a 'subject of interest' at one point - and was in contact with, and made prison visits to, a jailed terrorist.
Hearings on 'preventability' are due to start next month.
The inquiry resumes on Monday.
