A runaway car rolled backwards off a dealership forecourt and was stopped inches from speeding traffic on the M1 this morning in a “near-fatal accident”.

A short metal barrier miraculously caught the bottom of the white Nissan Qashqai as it smashed through a fence and fell down a four foot bank at the rear of the West London Motor Group (WLMG) Nissan dealership, off Watford Way, Mill Hill.

The safety breach occurred a short distance before the southbound slip road at Junction 2 (Hendon) at 10am and forced the closure of two lanes of the motorway for more than two hours.

London-bound traffic was backed up for more than a mile while the police and Highways Agency dealt with the incident, though all lanes have since been reopened.

The manager of the Nissan garage refused to comment on what caused the car to roll out of control when he was contacted by the Times Series this morning.

A police spokesman said the vehicle almost caused "a major accident that could have been fatal".

He added that officers would likely be "having a serious word" with the owners of the garage.

Investigators are now trying to establish how the brand new vehicle, rolled out of control before crashing through the six-foot wooden fence and coming to a rest inches from disaster.

A Highways Agency spokesman said it appeared the car had been shunted in a collision on the dealership forecourt.

Twitter user @RhinoSRN wrote that he saw “horrendous traffic “. Adding: “Looks like one of the salesman is getting his P45 tonight.”

The Times Series is awaiting further comment from the Highways Agency and has asked the Nissan dealership for a comment.

The car rolled off the forecourt of the Nissan dealership after reportedly being shunted by another vehicle