Video report by ITV News correspondent Sejal Karia
A police firearms officer says the security system outside Parliament "completely failed" on the day of the Westminster Terror attack.
PC Lee Ashby told an inquest into the five people who died, that PC Keith Palmer had been left unprotected at the gate when he was killed.
The court heard guidelines from January 2015 telling officers to focus on the gates when they were open hadn't been followed.
PC Ashby said he was never aware of them and was never challenged and instead followed instructions given by his sergeants in daily briefings.
Terrorist Khalid Masood crashed his car before stabbing PC Palmer, 48, to death at the gates to the Palace of Westminster before being shot three times by a plainclothes police officer on March 22, an inquest has heard.
Kurt Cochran, 54, Leslie Rhodes, 75, Aysha Frade, 44, and Andreea Cristea, 31, were also killed after being hit by the Hyundai Tucson being driven by Masood, 52, just 30 seconds before.
Consultant pathologist Ashley Fegan-Earl described the range of serious injuries suffered after the vehicle was deliberately used as a weapon, adding: ”It is as lethal as a knife or a gun.”
The inquest at the Old Bailey on Tuesday heard Mr Cochran, Mr Rhodes, and Ms Frade, suffered “unsurvivable” injuries during Masood’s rampage on Westminster Bridge.Mr Fegan-Earl said Ms Cristea’s head injuries would have been “highly likely” to have proved fatal even had the Romanian interior designer not been thrown 10ft into the air before plunging 41ft to the Thames below.
She was pulled out after five minutes spent lying unconscious and face down in the water, but died in hospital two weeks later.
Her cause of death was given as multiple organ failure due to head injury and immersion.
Jonathan Hough QC, for the coroner, queried whether Ms Cristea might have lived if her head had been lifted out of the water sooner after the inquest heard she had initially been hooked by the crew of a tourist boat after around two minutes and 18 seconds.
The pathologist said: “I suspect not.”
The inquest heard American tourist Mr Cochran pushed his wife Melissa out of the way moments before he was struck and toppled head first over the balustrade and onto the pavement below.
He suffered multiple bruises, fractures and brain injuries and his “survival period would have been brief”, pathologist Dr Simon Poole said.
A lawyer for Mr Cochran’s sister had questioned why medics had not done chest compressions after he flatlined at the scene.
Gareth Patterson QC said: “We heard ordinarily chest compressions would be carried out. Because the paramedic was treating the incident as a major incident no chest compressions were conducted.
“If that had been done, might that have made a difference?”
Dr Poole replied: “I don’t think so.” He added that the severity of the head wound and fractures to the skull were “unsurvivable”.
The inquest heard Mr Rhodes suffered a “devastating” head injury when he was struck by Masood’s rented car before being thrown on to the road.
He was taken to King’s College Hospital for treatment but died around 24 hours later.
Dr Fegan-Earl said: “The injury was devastating, unsurvivable and, in my opinion, it would have rendered him deeply unconscious straight away.
“There was no issue with the medical treatment he received and the formal cause of death was given as head injury.”
Pc Palmer suffered a total of 12 stab wounds or cutting injuries as Masood stood over him while he lay on the floor, driving two large knives into his body.
Consultant forensic pathologist Dr Robert Chapman said the fatal blow was an 18cm deep stab wound struck with severe force under his left arm, which damaged a rib before puncturing the officer’s lung and heart.
“In my opinion this injury was not a survivable one,” he said, adding that Pc Palmer would not have survived whatever medical attention he had received.
Dr Chapman also detailed a stab wound to Pc Palmer’s head as well as a stabbing injury that went completely through his left arm.
The official cause of death was given as haemorrhage as a result of a stab wound to the chest.