Marcelle O'Brien was sent to a home in Pinjarra, western Australia, run by the Fairbridge Society, at the age of four.
The then-Queen, wife of George VI, later intervened to ask whether she could return to the UK to be adopted.
But Fairbridge said it would not be in her "best interests", the Independent Inquiry into Child Sexual Abuse heard.
Mrs O'Brien said she suffered "mental cruelty" and "sadistic" treatment at the home where she was forced to do "slave labour".
She was molested by her school's deputy principal and caned, the hearing was told.
The inquiry, which covers England and Wales, heard Ms O'Brien had lived in a "loving and caring" home with a foster mother in Lingfield, Surrey, immediately before being sent abroad.
The foster mother later wrote to the Queen in an effort to get Ms O'Brien back to the UK so she could adopt her, the inquiry was told.
Subsequent correspondence between the Queen's Lady in Waiting and the Fairbridge Society was read out at the hearing.
A letter from the society to the Queen's Lady in Waiting said Ms O 'Brien was "happily settled at our school in Pinjarra - and which Her Majesty may remember visiting in 1928".
It went on to say Ms O 'Brien had many friends and to uproot her would "not be in the child's best interests".
The palace was apparently reassured by the Fairbridge response.
A letter from the Lady in Waiting to the society said "the Queen was pleased to hear" that it was considered to be in Ms O'Brien's interests to remain at the school.
Ms O'Brien told the inquiry panel: "They didn't take any notice. The Royal Family just didn't want to know anything. They stopped you from going back to your own original home."