For the past four years, every single new car or van on the roads in Britain has had to be fitted with a button that could save lives - but most people have no idea it exists.
New legislation that came into force at the start of April four years ago required manufacturers to fit an emergency call system known as eCall, which includes an SOS button fitted in the vehicle.
The system is activated when the vehicle is involved in a collision that is serious enough to activate the airbags. It automatically sends the vehicle's location to a 999 operator, enables drivers to speak with emergency operators and sends precise coordinates which means the emergency services know the exact location of the vehicle.
