There were "opportunities galore" for authorities to learn that the London Bridge terror attackers were planning an outrage before it happened, an inquest has heard.
Gareth Patterson QC, representing several victims' families, has outlined a number of instances where the three extremists were together and suggested there may have been clues to indicate they were plotting an attack.
Eight people were killed and 48 others injured when Khuram Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22, launched a van and knife attack on June 3, 2017.
Australians Sara Zelenak, 21, and Kirsty Boden, 28, along with Xavier Thomas, 45, Christine Archibald, 30, Sebastien Belanger, 36, James McMullan, 32, Alexandre Pigeard, 26, and Ignacio Echeverria, 39, died in the attack, which lasted less than 10 minutes.
Mr Patterson told the Old Bailey on Friday that in March all three attackers were at the Ummah fitness centre in east London, they had all been at the same address at some point, and that Butt had possibly been trying to buy a gun.
Investigating officer Acting Detective Chief Inspector Wayne Jolley said he did not agree that there had been missed opportunities surrounding the men, and said police would have been working with the intelligence they had.
Mr Patterson pointed to the repeated contacts between the men, including a barbecue at Butt's home in May at which Redouane was present, and noted that three identical knives were bought by Redouane the day after the barbecue.
"Any reasonably competent investigation should have been looking at Redouane at this stage, I would submit," Mr Patterson said.
Det Chief Insp Jolley said it would "depend on the intelligence at that time".
Mr Patterson told the court that all three men were at the gym in May "in the dead of night, speaking together in the street" in what he described as a "highly suspicious conversation".
Mr Patterson said a telephone was placed on the ground before the men began walking and talking during that meeting.
He described this as a "classic anti-surveillance technique" and suggested "the attack planning was there to be detected".
The court was also told that Zaghba held extremist views from childhood.
He celebrated the September 11 attacks in the US and had Islamic State flags on his Facebook page, according to writings by his mother.
He also tried to fly abroad to fight for IS, and Jihadist material was found on an SD card which was seized from him when he was stopped at an airport.
The court heard that by June 2017, Butt had taken himself off the WhatsApp network and his final status on it read "death is the start, may Allah have mercy on us".
Members of his family went on to disapprove of the attack, the court heard.
A message from his sister to a friend said: "He's a f***ing idiot. I f***ing hate him but he's my brother."
