Human error and a failure to follow basic safety procedures allegedly led to the tragic accident, the Mail on Sunday reported.

An engineer reportedly overrode an automatic safety lock, which allowed the ride operator to send the carriage, which was full of people, careering into a empty vehicle which had “stalled” further down the track, the newspaper said.

It added that both the employees that were involved were still working at the park, although in different roles, while a criminal investigation by the Health and Safety executive is reportedly underway.

Eighteen-year-old student  Leah Washington had her left leg amputated following the collision on June 2, while her boyfriend Joe Pugh, also 18, had both knees smashed. Twenty-year old Vicky Balch also had her right leg amputated three weeks after the crash.

An HSE spokesperson told the Mail on Sunday: “Our inquiry continues.” Merlin Entertainments added: ‘We continue to work closely with the HSE as it investigates the causes of the incident and we are unable to comment further.’