Video report by ITV News Correspondent Sejal Karia
The family of the ringleader of the London Bridge attack did not report "multiple warning signs" about the attacker to the authorities, a coroner has said.
As he concluded that the eight victims of the London Bridge terror attack were unlawfully killed, Chief Coroner Mark Lucraft QC also criticised a lack of barriers on London Bridge, enabling the van to hit pedestrians.
Less than three months before, terrorist Khalid Masood drove a car along Westminster Bridge, hitting and killing four people and injuring around 50.
Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22, killed their victims and injured 48 more in a van and knife attack on June 3, 2017.
They mowed down pedestrians on London Bridge before stabbing innocent bystanders at random in nearby Borough Market.
Xavier Thomas, 45, Christine Archibald, 30, Sara Zelenak, 21, Sebastien Belanger, 36, James McMullan, 32, Kirsty Boden, 28, Alexandre Pigeard, 26, and Ignacio Echeverria, 39, were all killed.
ITV News Correspondent Sejal Karia describes seeing and hearing the last moments of victims' lives during the inquest, and tells how families want the night to be remembered for the heroism of those who rushed to help, rather than the evil deeds of the attackers
Delivering his conclusion at the inquest, Mr Lucraft also said police and MI5 failed to recognise the threat posed by Butt, who associated with so-called Islamic State fanatic Anjem Choudary, appeared in the documentary The Jihadi Next Door and was able to teach the Koran at a primary school.
Before the attack, Butt had been under investigation yet authorities yet this was halted until just weeks before the attack due to funding pressures.
The inquest also heard how tip offs about Butt's extremism, including one from a family member, were not passed on to the relevant authorities.
However, Mr Lucraft did say he was happy that MI5 and counter-terrorism investigations leading up to the attack were thorough, and that other significant investigative opportunities which could have reasonably prevented deaths were not missed.
The inquest heard how former London Underground worker Butt hired the Hertz van which ploughed into pedestrians on the bridge, killing Frenchman Mr Thomas, 45, and Canadian Christine Archibald, 30.
Mr Thomas, a father-of-two, was catapulted into the River Thames and found dead three days later.
The van crashed into railings and Butt, Redouane and Zaghba ran amok around Borough Market with knives strapped to their wrists and fake suicide belts.
They set upon Sara Zelenak who had fallen over in her high heels then turned on James McMullan as he tried to help her up.
Nurse Kirsty Boden was stabbed after she went to the aid of French musician Alexandre Pigeard outside the Boro Bistro.
The killers also attacked Sebastien Belanger and Ignacio Echeverria who was fatally injured as he bravely fended off the attackers with his skateboard.
The rampage which also seriously injured 48 was over in just under 10 minutes when the terrorists were shot dead by armed police.
As well as criticising Butt's family members for failing to report multiple warning signs about him, Mr Lucraft also branded them unconvincing witnesses.
The coroner said the four members of the family who gave evidence during the inquest at the Old Bailey had known "something of his extreme views".
Butt's widow Zahrah Rehman, brother-in-law Usman Darr, brother Saad Butt, and sister Haleema Butt all gave evidence.
Summing up on Friday, Mr Lucraft said they had each accepted they should have done more at the time.
He added: "All of the family knew something of his extreme views.
"I have to say, I didn't find any of them convincing witnesses.
"Each has accepted that they should now have done more at the time."
Mr Lucraft said that while Saad Butt had claimed he was monitoring his brother, he had done little to do so.
Despite the coroner's criticisms of the family, Butt's brother-in-law Darr did report him to counter-terrorism officials in 2015, two years before the attack.
However, the tip off about his extremism was not passed on to the relevant authorities and no action was taken.
"I did my bit...the system failed and eight people died," Usman Darr told ITV News Security Editor Rohit Kachroo.
Despite the coroner clearing the police and security services of failing to stop the atrocity, victims' families believe more could and should have been done to prevent the deadly attack.
Speaking outside court following the conclusion, they focused on the lack of barriers on London Bridge, despite it being highlighted as a vulnerable location in the wake of the Westminster Bridge attack, and also the fact that Butt was known to authorities, as two areas in which the attack could potentially have been prevented.
Phillipe Pigeard, the father of French waiter Alexandre Pigeard said the deaths of the eight victims were "preventable".
Mr Pigeard criticised what he said were "missed opportunities to neutralise at least one of the attackers who was known as very dangerous" ahead of the attack.
He continued "despite many warnings from a police officer... who claimed it was an exposed area", no barriers were erected on London Bridge.
Mr Pigeard also paid tribute to nurse Helen Kennett, who stood with him outside court.
He said: "She came to help my son who was bleeding to death.
"She was stabbed too in a few seconds.
"I want to thank so much Helen for her courage."
He also paid tribute to Alexandre, who he said "was good for humanity" and was "gentle" and "marvellous", adding that the death was a "big loss".
The attack was similarly branded "preventable" by the girlfriend of Xavier Thomas who was hit by the van as he walked along the bridge with her.
Christine Delcros blamed authorities for a catalogue of "staggering" failings in the lead up to the attack.
"The absence of necessary preventative measures on the bridge, despite repeated, urgent warnings about the risk to pedestrians on the bridge from experts who knew the risks to the public; and imperfect communication between authorities meant that opportunities to identify all the attackers and disrupt their activities did not occur," Ms Delcros said.
"I find it staggering that Butt, a well-known extremist was allowed to work within the London transport network, to have access to and teach young children, and to rent and use a vehicle in a manner now too often encountered.
"I am dismayed SO15 (counter terrorism police) did not pass this critical information to any of his employers."
She also paid tribute to the "love and compassion" of the people who came to the rescue on the night, many risking their lives.
Mr Thomas' parents added: "It seems to us that a number of elements in the behaviour and demeanour of the terrorists failed to be picked up, although at least one of the attackers had been on MI5's radar for a very long time, and there had clearly been many opportunities to link him to both other accomplices, we believe opportunities that were missed and lost."
In a statement, Christine Archibald's parents Greg and Barbara spoke of their hopes that the coroner would recommend "appropriate measures be introduced so that MI5 is notified when a vehicle is rented by a person on their watch list."
They said: "Such a protocol might have prevented the death of Chrissy and others."
In his conclusions, Mr Lucraft noted extraordinary acts of bravery as police officers, medics and members of the public rushed in to help in spite of the danger.
Pc Charlie Guenigault was off duty when he took on the three terrorists with British Transport Police Pc Wayne Marques and Spanish banker Mr Echeverria.
In an interview, he said: "In my head I just see all three of them standing in front of me, knives in hand and fake vests on and that look of, 'We're going to kill you', basically that sort of anger in their eyes.
"When I got stabbed in the head it sounded like an explosion.
"It just felt like someone had punched me in the face with a massive fist...
"I could definitely feel it going into the skin, going into the bone."
The 27-year-old, who was awarded the George Medal, said he "played dead" and waited for the next blow which never came then resolved to "fight with everything I've got to stay alive".
He added: "At the inquest... people want to find blame for why such things happened - there are only three people to blame."
Helen Boniface, of Hogan Lovells, who represents six of the bereaved families, added: "The absence of barriers on London Bridge is an extremely important issue to all families we represent.
"This was clearly planned as a two-stage attack - had barriers been in place on London Bridge, they firmly believe this attack would not have taken place here at all and their loved ones would still be here today.
"The cumulative weight of intelligence known to MI5 and the police prior to the attack concerns the families that we represent.
"Kharum Butt was known to the authorities to be a dangerous person and it remains alarming that someone under active investigation can plan and perpetrate a terrorist attack."
She said there were "missed opportunities" to link the three terrorists who trained at the same gym.
Reacting to the coroner's conclusion that cleared police and security services of failing to stop the attack, the country's top counter-terrorism police officer said this did not mean authorities had been "complacent" since June 2017.
Metropolitan Police Assistant Commissioner Neil Basu said they had been "subjected to painstaking and painful investigations into lessons we could learn.
"With the benefit of hindsight certain things could have been done differently."
He added that the coroner had found that counter-terrorism officials "were thorough" and that the "post attack investigation found no evidence of long term calculated planning.
"Those closest to attacker knew nothing of their murderous plans.
"It will never be possible to stop every plot.
"We’re committed to getting better at what we do.
"The ultimate responsibility lies with these three criminals.
"If they wanted to defeat our country to break and divide us they failed.
"It made us stronger."
He added that all of the victims were "deeply loved" and should be remembered, while the three terrorists should be forgotten.
Mr Basu also praised those who "paid the ultimate price as they tried to help others".
How did the attack unfold?
Saturday morning - Khuram Butt tries to hire a 7.5-tonne lorry online but does not provide payment details so the rental does not go ahead
17.47 - Butt receives a text confirming the hire of a white Renault van, using a recently activated mobile phone, for 17.50 Saturday to 10am on Sunday
18.30 - Butt, Youssef Zaghba and Rachid Redouane drive in a red Corsa to Harold Hill, Romford, to pick up the van
19.17 - They arrive at an address in Barking, where Zaghba lived
19.38 - The trio leaves in the van heading into central London
21.58 - They drive over London Bridge. The van then travels over the bridge three times, and on the third occasion mounts the pavement and collides with pedestrians
22.07 - The van crashes into railings on the south side of the bridge, near the Barrowboy and Banker pub. The three men, armed with knives, run into Borough Market and stab numerous people, including two police officers
22.08- Police receive the first call about the incident
22.16- All three attackers are shot dead by eight firearms officers who discharged an unprecedented 46 rounds