On September 16, 2025, Prime Minister Sir Keir Starmer took the extraordinary step of ordering a new, independent investigation into the UK’s domestic intelligence agency, MI5, after it was revealed that the service had provided false evidence to three separate courts regarding its communications with the BBC. This latest inquiry, to be conducted under the oversight of the Investigatory Powers Commissioner, Sir Brian Leveson, comes on the heels of mounting judicial and public concern over MI5’s handling of a notorious neo-Nazi informant known only as Agent X.
The case at the heart of the scandal is as disturbing as it is complex. Agent X, a state informant embedded in far-right circles, allegedly used his privileged position with MI5 to coerce his girlfriend and ultimately attacked her with a machete. According to BBC reporting, MI5’s internal response to the situation was not only inadequate but actively deceptive: the agency repeatedly told judges that it had adhered to its policy of neither confirming nor denying the identities of its informants. In reality, as the BBC uncovered in February 2025, MI5 had privately disclosed Agent X’s status in phone calls to a BBC journalist in an attempt to discourage further investigation into the agent’s conduct.
When the BBC produced a recording of one such phone call, MI5’s narrative quickly unraveled. The service, which had aggressively defended its secrecy policy in court, was forced to admit that its statements to the judiciary were false. MI5’s Director General, Sir Ken McCallum, subsequently issued a public apology for what he described as a “serious failing” on the part of the service, both publicly and directly to the courts. In a statement, the Home Office echoed this sentiment, acknowledging the Home Secretary’s concern and emphasizing that “the Director General of MI5 has rightly apologised for this serious failing, both publicly and to the Courts.”
Despite the apology, the fallout was far from over. Two official internal inquiries were launched in the immediate aftermath of the revelations. However, both concluded there was no deliberate wrongdoing by MI5 or its officers. Instead, the inquiries chalked up the false evidence to “mistakes and poor memories.” This explanation failed to satisfy either the High Court or the Investigatory Powers Tribunal (IPT), both of which had been misled by MI5’s previous testimony. In July 2025, a panel of senior high court judges delivered a damning verdict: “The investigations carried out by MI5 to date suffer from serious procedural deficiencies,” they wrote, adding bluntly, “we cannot rely on their conclusions.”
The IPT, which oversees intelligence agencies’ use of surveillance powers, echoed these concerns later the same month. It not only rejected MI5’s explanations but also broadened the scope of its criticism, raising questions about the agency’s duty of candour—the legal requirement for public bodies to be open and honest in legal proceedings. The tribunal’s statement made clear that its concerns extended beyond just the possibility of contempt of court: “Our concerns are not confined only to the possibility of contempt of court but to wider questions of whether the duty of candour was fully complied with by MI5 and the government, and whether it is possible to identify individuals who were responsible for that failure, potentially including government lawyers.”
With the credibility of MI5’s own investigations in tatters, pressure mounted for an independent review. On September 16, the prime minister wrote to Sir Brian Leveson, instructing him to launch a new inquiry immediately. In a written statement to Parliament, Sir Keir Starmer made the government’s position clear: “I have now issued a direction to the Commissioner to commence this investigation immediately.” He further emphasized that the courts “will use the outcome of this investigation to determine their next steps in relation to the case of Agent X.”
This new investigation will be led by Deputy Investigatory Powers Commissioner Sir John Goldring, who brings significant experience from his previous role overseeing the Hillsborough inquests. Sir John will head a small, dedicated investigation team, and, crucially, will have access to legally privileged material where necessary. Sir Brian Leveson confirmed this arrangement, stating, “I have received Sir Ken McCallum’s assurance that the inspection team will have access to legally privileged material where this is required.”
The investigation’s terms of reference are ambitious and far-reaching. Not only will it examine the circumstances resulting in the “provision of false evidence to both the High Court and to the Investigatory Powers Tribunal,” but it will also scrutinize MI5’s compliance with the duty of candour in all proceedings connected with Agent X. The investigation is expected to identify whether individuals—including possibly government lawyers—bear responsibility for the failures, and to assess the adequacy of MI5’s internal processes for ensuring truthful and complete disclosure to the courts.
For those following the case, the stakes are high. The courts have made it clear that they will await the findings of this new investigation before deciding whether to initiate contempt of court proceedings against any MI5 officers or other individuals. As the High Court put it, it would be “premature” to make such a determination in the absence of a credible, independent inquiry.
Meanwhile, the wider implications for public trust in the intelligence services and the government’s oversight mechanisms loom large. The BBC’s original reporting exposed not just the failings of a single agency or individual but systemic weaknesses in how sensitive information is handled and disclosed in the UK’s legal system. The episode has also put a spotlight on the crucial importance of the duty of candour, a principle designed to ensure that courts can rely on the evidence presented to them by state bodies—something that, in this case, was gravely undermined.
With Sir Brian Leveson’s office itself having been provided with false evidence by MI5 in the past, the new investigation will be watched closely by legal experts, politicians, and the public alike. As the inquiry gets underway, questions remain about how such a breakdown in candour and accountability could have occurred in one of the country’s most sensitive and secretive agencies.
All eyes are now on Sir John Goldring and his team as they begin their work. The outcome of their investigation will not only shape the future of the Agent X case but could have lasting repercussions for the oversight of intelligence operations in the UK.
