MI5 has admitted to providing false evidence to three courts regarding a neo-Nazi informant who used his position within the intelligence agency to violently abuse and terrorise his girlfriend. The woman, identified only as Beth, was attacked with a machete and threatened into silence by the agent; MI5 has since paid her compensation and issued a public apology in an unprecedented move. Beth's legal representatives are now seeking contempt of court proceedings against MI5 Director-General Sir Ken McCallum and individual officers involved, arguing the false evidence was sustained and institutional rather than attributable to a single "bad apple".

In July, Deputy Investigatory Powers Commissioner Sir John Goldring concluded that MI5 had committed "serious and systemic failings", with one senior officer lying repeatedly and another misleading colleagues. The agency initially confirmed the informant's status to the BBC to discourage publication, then later claimed it could "neither confirm nor deny" the relationship in court proceedings. Anyone found in contempt of court faces potential imprisonment of up to two years or a fine. MI5's legal representatives contest the case, arguing there is no basis for holding the director-general vicariously liable, though the judges' final judgment is pending.