See Section 6: Privacy of the Editorial Guidelines.
The BBC must not infringe privacy without good reason. In order to exercise our rights of freedom of expression and information, we must work within a framework which respects an individual's privacy and treats them fairly, while investigating and establishing matters which it is in the public interest to reveal.
Private behaviour, correspondence and conversation should not be brought into the public domain unless there is a clear public interest. The law also protects privacy in the United Kingdom, including the Human Rights Act 1998.