His gummy grin is irresistible, a beaming smile to melt hearts. It's a sight Cameron Carville's parents feared they might never see.

Cameron was born with a heart defect which needed urgent surgery.

But while struggling to cope with his life-threatening condition, his parents, Steve and Fiona, were dealt an even more devastating blow.

An ambulance transferring three-day-old Cameron between hospitals was in collision with a police car answering a 999 call.

The ambulance overturned and Cameron was flung from his cot. Tubes keeping him alive were ripped from his body and his heart stopped.

Steve and Fiona, who were travelling in a car behind the ambulance, heard the collision as they rounded a bend and screeched to a halt in front of the horrifying scene.

It was the middle of the night and in the darkness and confusion it took several minutes to find Cameron. Lying lifeless beneath a stretcher in the wreckage, he had a dent in his skull and was covered in blood.

Recalling the worst night of her life, Fiona, 29, from Eastbourne, said: "It was unbearable. We thought his heart defect was the worst thing that could happen to him and then this occurred. I was just in total shock."

A nurse and doctor who were travelling with Cameron managed to start his heart and another ambulance took him to Guy's Hospital.

Doctors treated Cameron for a fractured skull and bruising to the brain but his injuries were so severe he was unable to undergo heart surgery for two weeks. During the wait his condition prevented oxygen moving around his body properly, adding to the worry.

Now, six months on, Steve and Fiona's prayers have been answered and Cameron is a healthy - and clearly very happy - little boy.

Back home he is the picture of health and loves playing with his two-year-old sister Sorcha.

The only signs of his traumatic early days are a scar on his chest from his heart operation and a small dent in his head.

Fiona said: "He had a terrible time and I do sometimes still see it all in my mind but I'm not going to let it hinder or get in the way of our lives.

"His heart is working perfectly and neurologically he seems normal, even advanced in vision and head control, so we are hoping everything will be fine for the future."

The ambulance and the police car, both using sirens and flashing lights, collided in south London at 3am on February 10.

The ambulance driver was critically injured but neither of the officers in the car needed hospital treatment.

An investigation into the accident has been carried out by the Police Complaints Authority and a file passed to the Crown Prosecution Service.