MI5 will need proof to be believed in future, says Leveson after BBC investigation

The man responsible for overseeing the conduct of MI5 has said it will now have to provide proof to be believed by judges, after a BBC News investigation exposed how the security service lied to three courts. Lord Leveson, the investigatory powers commissioner and a former Court of Appeal justice, said that as a judge "if the security service said something to me, then I would accept it". But he said courts would now be "far more reluctant to accept, without evidential proof, things that are said in the future".

Lord Leveson praised the impact of the BBC's investigation into an abusive MI5 agent, which he said had led to changes in how informants are managed. The BBC's investigation had "hit the intelligence community hard", including security services around the world, he said. The BBC investigation exposed how a neo-Nazi informant - known as Agent X - used his state role as a tool of abuse.

He coercively controlled his partner, known by the alias Beth, and attacked her with a machete. He had previously abused another woman and threatened to kill her child.