He only told one person outright - Julie. For a variety of reasons. No one believes Julie would approach the police, compile a 24 page WS & testify because they split up.
However he was itching to tell other people & indirectly did. He would have become more open the safer he felt.
The opposite occurred in his police interviews. Bamber basically saying 'yeah we both know I'm guilty. But you need to get a conviction in court'.
He had to be more open in court. But struggled.