Do you Know? Queen Elizabeth II wrote a secret letter that can`t be opened for 63 years. It`s kept on a vault in Sydney The letter was written by her in November 1986. The letter is hidden inside a glass case in a secure location. It can`t be opened until 2085 since it`s hidden behind a glass case in a secure location. Queen Elizabeth II visited Australia 16 times during her reign as head of state.