POLICE are appealing for help in solving a mystery collision on the M4 on Friday afternoon that left a 69-year-old woman seriously injured.

At around 4.05pm the woman, from the South Wales area, was the front-seat passenger in a beige Citroen C4 VTR travelling westbound between Junctions 16 and 17 of the M4.

For reasons not yet apparent to police investigators, the car, driven by a 71-year-old man, lost control and veered from lane three onto the hard shoulder, colliding with the Armco barrier.

The male driver, also from South Wales, suffered minor injuries and was taken by ambulance to hospital in Bristol.

The front seat passenger suffered more serious and potentially life-threatening injuries.

An RAF medic had been passing at the time of the incident and was the first on the scene to provide medical assistance.

A Wiltshire Air Ambulance spokesman said: “This was a true multi-agency response with Wiltshire Police and Wiltshire Fire and Rescue Service all working together with South West Ambulance Service Trust crews at the scene, and a special mention to the RAF medic who was passing and first on scene to offer his assistance.”

The eastbound carriageway of the M4 was closed for the Wiltshire Air Ambulance to land and take the woman to Southmead Hospital, where she remains.

The motorway was closed for around four hours while police conducted their investigations, but the cause of the collision is still a mystery.

PC Hutton, of the Tri Force Roads Policing Team, said: “Wiltshire Police were called at approximately 4.05pm to reports of a single-vehicle road traffic collision.

“A beige Citroen C4 VTR had been travelling westbound on the M4 motorway between Junctions 16 and 17.

“For reasons as yet unknown, it seems the Citroen lost control, veering from lane three on the main carriageway onto the hard shoulder and colliding with the Armco barrier.

“The driver, a 71-year-old male from the South Wales area, suffered minor injuries.

“However, the passenger, a 69-year-old female, also from the South Wales area, sustained what are thought to be life-changing injuries.

“Both were taken to Southmead Hospital, the female by air ambulance, and the male by land ambulance.

“The motorway was closed for around four hours while police carried out investigations.”

Police are appealing for any witnesses to the collision to contact PC Hutton at the Tri-Force Roads Policing Team via the non-emergency number 101.