Sir John Saunders, chairman of the public inquiry into the bombing, has published volume one of his report which laid bare a series of failings by SMG, the venue operators, Showsec, the stewarding and security contractors and British Transport Police (BTP), responsible for policing the arena complex beside Victoria railway station.
Paul Hett, father of Martyn Hett, 29, who died in the bombing, said: “We entrusted the lives of our loved ones to organisations who we believed had a duty of care to protect them.
“This inquiry has rightly found that we were failed by them on every level.
“This atrocity should and could have been prevented, and 22 people would not have lost their lives.”
Both the organisations themselves and their employees were criticised for security arrangements at one of Europe’s busiest entertainment venues, where suicide bomber Salman Abedi murdered 22 bystanders after an Ariana Grande concert on May 22, 2017.
The family of Eilidh MacLeod – the 14-year-old from Barra who died in the bombing – have previously highlighted their devastation and anger at the situation.
They said: “Eilidh loved her life and everything in it - and it wasn't hard to love her right back.
"We still have to stop ourselves calling out her name for our dinner, that will never stop.
"Anger, fear, resentment and heartbreak is something we all have to live with.
"No parent who ever takes their child to a concert should ever have to take them home to bury them.”
June Tron, mother of Philip Tron, 32, who was killed in the attack, said: “Every life taken in this horrendous attack has destroyed the lives of those close to them and we don’t want anyone else to go through what we have following the loss of Philip.
“It has been extremely hard to listen to evidence which has highlighted how our Government has failed to take extra steps to ensure security is as it should be at venues like this across the country, and how organisations who are supposedly experts in running such venues and events can make so many basic mistakes relating to safety and security."
Figen Murray, the mother of Martyn Hett, is leading a campaign for Martyn’s Law, to improve safety at public venues.
She told the PA news agency: “It’s clear from the first report of the inquiry that venue security needs to be improved to help prevent further terrorist attacks.
“It shows that sufficient protection and preparation for any potential incident is an obligation for venue holders.
“But now after this report we are one step closer to ensuring that a difference can be made."
Neil Hudgell, of Hudgells Solicitors, who represents the bereaved families, said collective failings made the arena a sitting target for terrorists.
He added: “As a result of these combined failings, thousands of young people who attended the concert on that night were left an open and vulnerable target for terrorists because the security around the venue and event was nowhere near what it needed to be.
"There were gaps and failings galore.”