The Metropolitan Police have launched a review of the investigation into a car crash at a school which killed two eight-year-old girls.

According to the force, the review was opened after “concerns” were raised by the families of Nuria Sajjad and Selena Lau, who died after the crash at the Study Prep school in Wimbledon, south-west London, on July 6 last year.

The families said they remained “unconvinced” that the investigation was conducted thoroughly after it was announced last week that the driver of the 4×4 had suffered an epileptic seizure behind the wheel and would not face criminal charges.

In a statement on Thursday, the Met said: “Having listened to concerns from the families of both Nuria and Selena – and other parties affected – we are committed to addressing their questions, and the Specialist Crime Review Group (SCRG) will therefore be carrying out a review of the investigation.”

The force said officers worked “tirelessly through every detail of the incident” to ensure a complete investigation.

The former headteacher of the school, who held the role at the time of the crash said she feels “let down” by the police investigation.

Helen Lowe told the BBC: “I think the words ‘thorough’ and ‘tireless’ suggest that you would have a body of evidence that you would be able to share… but in some areas there was just a complete lack of knowledge, of basic information.

“Maybe when they go away and look at the evidence, they will remember the answers. But there were a number of occasions where they weren’t sure if something had been done, or they couldn’t remember.

“At this moment in time, it would appear that I have been let down by them.”

In a joint statement issued after it was announced that the driver, Claire Freemantle, would not face criminal charges, the girls’ families said: “We remain unconvinced that the investigation has been conducted thoroughly.

“We remain unconvinced that the Crown Prosecution Service (CPS) have reached a decision based on all the facts. Justice has neither been done, nor has been seen to be done today.”

They added that Nuria and Selena “deserved better”.

Ms Freemantle expressed her “deepest sorrow” in a statement to the PA news agency and said she had “no recollection of what took place” after losing consciousness.

The school had been celebrating the last day of the summer term when the tragedy unfolded.

Several other people were injured when the 4×4 crashed through a fence and hit a building.