Westminster attacker Khalid Masood was lawfully killed after murdering five people, an inquest has concluded.
He died after being shot by a minister’s bodyguard in the Palace of Westminster on 22 March last year.
Masood had ploughed through pedestrians on Westminster Bridge in a car, killing four, and stabbed PC Keith Palmer.
The Met Police apologised after the coroner identified “shortcomings” in the security system at the palace where PC Palmer died.
Metropolitan Police assistant commissioner Neil Basu said: “Even the possibility that the Metropolitan Police Service lost the chance to prevent the murder of one of our officers is unacceptable and we are deeply sorry.
“Security arrangements have substantially changed since the attack and we will do everything possible to improve that position further.”
An earlier inquest into the death of the five people killed by Masood heard that there were no armed officers at the entrance to Parliament for almost an hour before PC Keith Palmer was stabbed.
Mr Basu also addressed criticism of Sir Craig Mackey, who was the Met Police’s acting chief at the time and who witnessed the murder of PC Palmer from a locked car.
Speaking about the controversy over Sir Craig’s decision not to confront Masood, he said there had been some “abhorrent remarks made”.
“Both I and the investigators know there is nothing that Craig could have done to have stopped Masood or to have saved PC Palmer or any others from being injured.”
It took an inquest jury at the Old Bailey two hours and 22 minutes to come to the verdict.
They found that Masood was intent on inflicting “serious harm” when he carried out the attack.
The jury said he had been issued with verbal warnings but “continued to move toward the close protection officers at speed” before being shot.
Coroner Mark Lucraft QC had earlier directed the jury to return a lawful killing verdict on the grounds that the bodyguard who shot Masood believed opening fire was necessary to defend himself and others.
Speaking outside the court, Mr Basu said the attack lasted 82 seconds but had the most “appalling consequences”.
“The two armed close protection officers who confronted this individual acted with great courage.
“They undoubtedly prevented others from being injured and further loss of life.
“I pay tribute to their tremendous professionalism and their bravery.”
During the inquest, the bodyguard who shot Masood broke down as he described how he feared for his life.
“He was carrying two large knives… covered in blood. He was going to kill me,” the close protection officer said.
He described drawing his Glock pistol on seeing Masood running towards him, and shouting at the attacker to drop the knives, before firing three times.
Mr Basu said: “It will be hard to forget the heartbreaking testimony of the officer who shot this terrorist.
“It’s a stark reminder that our officers are human and the distress taking another life causes them even if that individual is a terrorist and even if there is no alternative.”