The woman who found an abandoned baby boy while walking her dog has told how the child was beginning to show signs of hypothermia.

Pippa Whitbread, a nurse, of Hilltop Gardens, Islip, spoke as police appealed for help in tracing the driver of a BMW car seen leaving the scene towards Oxford just hours before the discovery.

The baby was discovered in blankets and a plastic bag at an allotment off Wheatley Road in freezing conditions just hours after he was born.

Miss Whitbread was walking her dog, Zak, at about 6pm on Friday when the pet started to sniff a plastic bag left on a grass verge at the entrance to the allotments.

The nurse looked inside and found the baby.

"I usually just get in the car and drive home but Zak started sniffing this plastic bag and then I heard the baby crying," she said.

"I was incredibly calm about it and just picked him up, felt that he was warm and okay, and took him home. It's only there where I started to feel a little shocked."

Miss Whitbread said she realised that the baby was starting to show symptoms of hypothermia so she took him to the accident and emergency department at the John Radcliffe Hospital in Oxford.

She added that Zak himself was an abandoned puppy. Six years ago, Miss Whitbread found him on her doorstep and tried to find a home for him but eventually looked after the puppy herself.

She said: "It's amazing really that six years ago I found Zak abandoned on my doorstep and now Zak finds a little baby."

She has named the baby William after her grandfather.

She said: "My grandfather's got no teeth and neither had the baby, he looked like a little old man so I named him after my grandfather."

The mother has still not been found and police have launched an appeal to health professionals in Oxfordshire and neighbouring counties for information about an expectant mother who cannot now account for her baby.

Det Sgt Bob Smith, of Kidlington CID, said: "Our prime concern is to trace the mother and if appropriate, re-unite her with her son.

'This must be a very traumatic time for her and she might consider contacting the police to explain the circumstances."