There is a phrase that echoes through every major institutional scandal of our time. You hear it from boardrooms and dispatch boxes alike. It is delivered with a furrowed brow and apparent sincerity:
“I didn’t know.”
This week, Prime Minister Keir Starmer used that defence in relation to Peter Mandelson’s failed security vetting. The man he appointed as Ambassador to the United States – whose vetting he told Parliament had been properly conducted – was later arrested on suspicion of misconduct in public office linked to his dealings with Jeffrey Epstein.
Whether Starmer knew or did not know, neither answer reflects well on him. This is not primarily a question of knowledge. It is a question of responsibility.
Mandelson was appointed in late 2024. Even at the time, there were known concerns within senior government circles about his relationship with Epstein, a convicted sex offender whose connections with powerful figures continued long after his conviction. UK Security Vetting initially denied clearance, but that decision was overruled within the Foreign Office. It remains unclear who authorised that override.
Before and after Mandelson’s appointment, Starmer repeatedly assured Parliament that “full due process” had been followed and that no red flags had been raised.
However, reporting has since suggested that senior officials were aware this was not the case while those assurances were still being made. The Guardian revealed this on 17 April 2026. That same night, the Foreign Office’s top official, Olly Robbins, was forced out.
The Ministerial Code requires ministers who have inadvertently misled Parliament to correct the record at the earliest opportunity. Starmer has also publicly championed a statutory “Duty of Candour” for public officials – legislation he promised would be introduced following the Hillsborough campaign. It has not been delivered. Instead, proposals stalled after the government sought exemptions for the security services: the very bodies involved in the vetting process at the centre of this case.
Starmer understands what a duty of candour means, and why it matters. On Tuesday evening (14th April) – when, according to his own account, he was informed of the failed vetting – that duty applied to him as well. Prime Minister’s Questions took place the following day. He said nothing. The story became public on Thursday. Only on Friday did he finally announce he would address Parliament the following week, promising to set out “all the relevant facts in true transparency.”
That sequence matters. Accountability is not only about what is eventually said, but when it is said.
Starmer’s own words are revealing:
“That I wasn’t told that Peter Mandelson had failed security vetting when I was telling Parliament that due process had been followed is unforgivable.”
The effect of that statement is to place the focus on failures within the system beneath him, rather than on the decisions taken at the top. But this was his appointment, and these were his assurances to Parliament. Responsibility does not diminish because information failed to reach him. If anything, it sharpens.
If he knew, then Parliament was misled deliberately. Under the Ministerial Code, that is a resignation matter.
If he did not know, then senior officials withheld critical information while false assurances were being given to Parliament. That points to a serious failure of organisational culture – one for which the Prime Minister is ultimately responsible.
In February, Starmer told Parliament that vetting had flagged the Epstein connection but granted clearance. At that point, any leader exercising reasonable diligence might have asked to see the report itself. There is no indication that happened. This is a familiar pattern: when not knowing becomes an acceptable defence, the incentive to ask difficult questions begins to erode.
We have seen this before. During the Horizon scandal, senior leadership claimed they were unaware of critical failures within their organisation. The lesson was clear: leadership carries a duty not just to act on information, but to ensure that information reaches them in the first place.
This principle is well established in the corporate world. The Companies Act 2006 makes clear that ignorance does not automatically absolve a director where a reasonable person in their position should have known. A director can be disqualified or prosecuted. A Prime Minister, by contrast, is held to account largely through political mechanisms. The Ministerial Code has no independent enforcement. It relies, in effect, on those it governs.
This is not only about one appointment or one Prime Minister. The protection of the powerful – by institutions, by colleagues, by cultures of silence – causes real and lasting harm. We have seen it in the Horizon scandal. We see it in the long shadow of the Epstein case, where warning signs were repeatedly overlooked and the consequences fell overwhelmingly on the vulnerable.
That culture does not emerge by accident. It is built through decisions that reward compliance over candour, that discourage uncomfortable truths, and that prioritise the protection of institutions over the telling of them.
Whistleblowers are the immune system of any healthy organisation. When they are suppressed, failure becomes not just possible, but inevitable. Accountability means creating the conditions in which difficult truths can reach those in power – and acting on them when they do.
Until the cost of institutional silence exceeds the cost of speaking up, we will continue to see the same pattern repeated. And those at the centre of it will continue to reach for the same defence:
“I didn’t know.”
