A young mother who lay undiscovered in a crashed car for three days after the incident was reported to police would probably have survived if she had been found sooner, a court has heard.

Police Scotland have admitted their failings “materially contributed” to the death of Lamara Bell in July 2015.

The force on Tuesday pleaded guilty to health and safety failings, following the deaths of John Yuill, 28, and Lamara Bell, 25, who died after their car crashed off the M9 near Stirling.

Ms Bell’s mother welcomed the conviction, saying: “The absence of answers and recognition has been the biggest strain because it is the not knowing that makes everything worse.

“It has taken a long time for this conviction to be secured but it is a huge relief that Police Scotland has finally admitted being at fault for Lamara’s death.”

Despite a call being made to police on the day of the crash, it took them three days to respond.

When officers finally arrived at the scene, Mr Yuill was found to be dead and Ms Bell died four days later in hospital.

The High Court in Edinburgh heard that Ms Bell was conscious and said, “help me, get me out” to a member of the public who found her in the vehicle after noticing it on July 8.

The mother of two had suffered serious injuries including to her skull and brain and developed acute meningitis. However, prosecutor Ashley Edwards QC said experts agreed she would probably have survived if treated in time.

Ms Edwards said: “Various experts from a range of specialisms agreed that had Lamara Bell been admitted to hospital within six–eight hours of her primary injury, the secondary complications of the injury leading to her death would have been easier to manage and would have been substantially avoided.

“This would in all probability have led to her survival, albeit with some long-term neurological disability.”

Mr Yuill, a father of five, died at the scene of the accident either at or shortly after the time of the accident, which is estimated to have happened at 6.17am on July 5.

Experts agreed that his “very severe injuries” were not survivable regardless of the timing of medical intervention.

The office of the Chief Constable of Police Scotland on Tuesday admitted that it failed to ensure that people, including Mr Yuill and Ms Bell, were not exposed to risks to their health and safety by failing to provide an “adequate and reliable call-handling system” between April 1 2013 and March 1 2016.

It also failed to ensure the system was “not vulnerable to unacceptable risks arising from human error” and to ensure that all relevant information reported by members of the public was recorded on a Police Scotland IT system so that it could be considered and a police response provided where appropriate.

The force admitted that as a result, members of the public were exposed to risks to their health and safety and, in particular, on July 5 2015, a police officer at the force call-handling centre at Bilston Glen Service Centre failed to record a phone call from a member of the public reporting that a vehicle was at the bottom of an embankment at the side of the eastbound junction nine slip road from the M80 on to the M9.

The phone call was not recorded on any Police Scotland IT system and no action was taken.

The force admitted Ms Bell and Mr Yuill remained “unaided and exposed to the elements” in the car between July 5 and 8 2015, and that the failings “materially contributed” to her death on July 12 that year at the Queen Elizabeth University Hospital in Glasgow.

The force pleaded guilty to breaching the Health and Safety at Work Act 1974.

The court heard Mr Yuill and Ms Bell went on a camping trip with friends on Saturday July 4 2015 to Loch Earn.

Mr Yuill, who held a provisional licence, was driving his car, supervised by a friend with a full licence, however, the following morning he drove off in his car with Ms Bell, leaving the others sleeping.

When they failed to return home by evening, their parents called the police to report them missing and a missing persons investigation was launched.

The court heard this was conducted “efficiently” and that one line of inquiry was that the couple had been involved in a crash as Mr Yuill was an “inexperienced” driver.

Ashley Edwards QC, prosecuting, told the court a member of the public noticed a blue car partly obscured by bushes off the M9 motorway and called police at 11.29am on July 5 to report it but the call handler did not create an incident for this call on the Storm system.

The court heard that on July 8 another member of the public noticed a blue car at the bottom of the embankment and went to investigate.

Ms Edwards said: “On closer inspection he saw it was a blue car with two occupants. He saw a female moving her arms and moaning. She said, ‘help me, get me out’ and he tried to reassure her and called 999.”

Emergency services attended and Ms Bell, who was in the passenger seat, was airlifted to hospital with serious injuries where she died on July 12.

Sir Stephen House, who was chief constable at the time of the incident, stepped down from the role at the end of 2015 following controversy over the deaths.

The crash took place against a backdrop of the restructuring of police control rooms following the creation of Police Scotland.

This saw control centres in Glenrothes and Stirling closed in early 2015 and their work transferred to Bilston Glen, however, many staff did not want to relocate, leading to concerns about insufficient staffing.

Serving police officers who were trained in the Storm system to call handler level were offered overtime to help with staffing, and these included the officer who took the initial call about the July 5 crash.

The court heard there had been no concerns about his work previously and that the incident was due to “human error”.

The current Police Scotland Chief Constable, Iain Livingstone, was in court for the hearing and offered his “profound apologies and sincere condolences” to the families of Ms Bell and Mr Yuill.

Murdo Macleod QC, representing Police Scotland, said that reviews of the call handling system were carried out in the wake of the tragedy and that the 38 recommendations have now been implemented in full.

He said: “Through significant investment and time and resources, concerted efforts have been made to ensure robust measures are in place to mitigate the risks and lessen the risk that something else might happen again.”

Lord Beckett adjourned the case to consider matters before he announces the sentence.