The head of the Metropolitan Police has said it is "simply wrong" to criticise her deputy for remaining in his car during the Westminster terror attack.
Cressida Dick said that accusing Sir Craig Mackey of cowardice was "confused, unpleasant, personalised and ignorant" and was "simply not supported by the evidence".
Her comments came after an inquest concluded that Westminster attacker Khalid Masood was lawfully killed.
The Muslim convert mowed down pedestrians on Westminster Bridge in a hired SUV, killing four people and seriously injuring 29 others, before stabbing PC Keith Palmer to death.
Jurors at the Old Bailey heard that Sir Craig, one of the country's most senior police officers, stayed in his official car as Masood murdered PC Palmer during the attack in March last year.
Sir Craig, who acting commissioner at the time of the attack, has faced calls to resign after telling the inquest he locked the doors and remained in the vehicle due to having no personal equipment or a radio.
Defending Sir Craig, Ms Dick said: "These criticisms are simply not supported by the evidence.
"The attack in New Palace Yard occurred and was stopped in seconds. Sir Craig had absolutely no opportunity to stop the killer or save PC Palmer.
"Anyone who suggests otherwise is simply wrong.
"The actions he was able to and did take were to protect the unarmed police staff colleagues who were in the car with him. He went on to lead the Met's response to the attack with distinction."
Chief coroner Mark Lucraft QC defended Sir Craig's actions as "sensible and proper and intended to protect others in the car".
In his summing up, Mr Lucraft said: "It is clear from the evidence of Sir Craig there was nothing he could have done to stop Masood.
"Pc Palmer was under attack practically as soon as Sir Craig saw the attacker."
Following the inquest, the Met's counter-terror chief Neil Basu accepted there were "shortcomings" in security on the day of the Westminster ttack.
He said: "In relation to PC Keith Palmer's death, the chief coroner identified shortcomings in the security system at the Palace of Westminster, including the supervision of those engaged in those duties.
"We unreservedly accept those conclusions."
Mr Basu added that even the possibility of losing the chance to protect any police officer is "unacceptable" and that the force are "deeply sorry".
In defence of Sir Craig, he said: "Can I turn to some of the abhorrent remarks circulating about the deputy commissioner Sir Craig Mackey?
"Both I and the investigators both 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."
Masood, 52, crashed into railings before storming through gates near the Houses of Parliament with two knives during the 82-second-long attack.
He then Masood stabbed unarmed PC Palmer to death before being shot dead by a bodyguard who rushed to the scene.
The jury found that he was intent on inflicting "serious harm, and/or take a life" as he continued without stopping or changing direction.
He had been issued with verbal warnings but "continued to move toward the close protection officers at speed" before he was shot, the jury said.
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Mr Lucraft had earlier directed the jury to return a lawful killing verdict as the bodyguard who shot Masood believed it was necessary to open fire in defence of himself and others.
Masood's rampage was stopped by a close protection officer identified only as SA74 – who was on site working as a bodyguard to a government minister.