BABY Caroline, who was found in a Camberley car park a year ago, celebrated her first birthday last Saturday.
Surrey County Council, which is now responsible for her welfare, used the occasion to issue a heartfelt plea for her mother to come forward.
Caroline, named after the hospital sister who cared for her immediately after she was found, is said to be progressing well with her adoptive parents.
But Felicity Budgen, deputy head of the county's children's service, said they still wanted the baby's natural mother to contact them.
"It is important for adopted children to have a sense of where they came from and why they were adopted," she said.
The identity of Caroline's mother remains a mystery despite nation-wide publicity to trace her.
She disappeared after leaving her new-born baby wrapped in a shawl in Pembroke car park.
After initially being looked after at Frimley Park Hospital, the baby was adopted by a family whose identity remains secret.
In an open letter to Caroline's natural mother, they say: "Caroline is the most beautiful, sweet natured and gentle baby whose smile radiates warmth and goodness.
"We hope you will read this letter and be assured that Caroline is happy, loved and secure in her new adoptive home."
Expressing the hope that her natural mother will summon up the courage to come forward, they add: "We think about you often and realise how difficult it must be at times to carry your secret."
If Caroline's natural mother wishes to know more she should contact Shona McGarry, of the county's children's service, on 01932 566272 or 01483 517898.