With his mother suddenly passing out while cruising at 70 mph along a three lanes of traffic, a nine-year-old boy took over the steering wheels of their car before parking it to safety.

Jonathan Anderson said the car lost control and hit the road's central barrier when her mother, Marion blacked out while they were traversing the A38 in Plympton, Devon.

Jonathan said he hit the brakes and put the hazard lights on, before steering the back across three lanes and simply parked it on the side street.

Emergency services responding to the incident said Jonathan averted a possible serious vehicular accident through his heroic deed.

"He is my little superhero. The last thing I remember is driving over the flyover to take Jonathan to school," said Marion.

"When I was lying in A&E the nurses told me what a miracle it was and how clever my son is. I have always been proud of him but even more so now," the 34-year old mother who runs a curtain-making business said.

"Mommy passed out so I held the steering wheel, pulled the handbrake and put the hazard lights on. The car stopped and the windscreen smashed," Jonathan said. "It was scary because I have never driven a car before."

Jonathan, who is suffering from Asperger's Syndrome, a form of autism, is expected to be awarded a special bravery certificate.