Lib Dems report Prime Minister to ethics adviser for breach of Ministerial Code

The Liberal Democrats have formally reported Sir Keir Starmer to Sir Laurie Magnus for failing to notify Parliament as soon as he knew Lord Mandelson failed security vetting.

The Liberal Democrats' report to ethics adviser Sir Laurie Magnus argues the Prime Minister has breached the Ministerial Code, which states that it is of "paramount importance" that Ministers give accurate information to Parliament and correct any errors "at the earliest opportunity".

A government spokesperson confirmed this week that the Prime Minister was informed "earlier this week" that Lord Mandelson had actually failed security vetting. The revelations about the vetting failure were reported late afternoon on Thursday.

The Liberal Democrats have pointed out that despite knowing Mandelson had failed vetting, the Prime Minister failed to update Parliament during Wednesday's Prime Minister's Questions (PMQs), choosing instead to withhold the information until it surfaced through the media.

The party's Cabinet Office spokesperson Lisa Smart has written to Laurie Magnus to report the potential breach of ministerial code code.

Lisa Smart MP, Liberal Democrat Cabinet Office Spokesperson, said:

“The Prime Minister failed to tell Parliament that he knew Mandelson had been denied vetting on Wednesday, presumably crossing his fingers and hoping the truth would not come out. What a shameful way for a Prime Minister to behave.

“To stand in front of the dispatch box and deny Parliament such crucial information looks like a serious breach of ministerial code. That's why I've written to the ethics adviser to report this breach and ask him to investigate at the earliest opportunity.

“Starmer made catastrophic errors of judgment from the very beginning of the Mandelson scandal and it seems he has just kept on making them. His position is now untenable.”

ENDS

Notes to Editor

Please see the text of the letter, sent by Lisa Smart MP, Liberal Democrat Cabinet Office Spokesperson, below:

Dear Sir Laurie,
 

I am writing to request that you initiate an investigation into a potential breach of the Ministerial Code by the Prime Minister, the Rt Hon Sir Keir Starmer.
 

A government spokesperson has confirmed that the Prime Minister became aware “earlier this week” that Lord Mandelson had failed security vetting.
 

Under Section 1.6.C of the Ministerial Code, it is not only expected but “of paramount importance” to give accurate, truthful information to Parliament and that ministers “correct any inadvertent error at the earliest opportunity”. 
 

The Prime Minister had previously told the House of Commons that “full due process” was followed (he made these remarks to the House on 10 September 2025).

However it appears that upon being made aware that Mandelson failed vetting, the Prime Minister did not immediately update the House of Commons.
 

By withholding this information (which is of significant national importance) from Parliament over the course of the week, until it surfaced through other channels, the Prime Minister appears to have failed in his obligation to correct inadvertent errors “at the earliest opportunity”. He had one such clear opportunity at Prime Minister's Questions on Wednesday, yet failed to correct the record. I would make the case that this represents a clear breach of the Ministerial Code. I therefore urge you to investigate whether the Prime Minister's failure to report this information constitutes a formal breach.
 

I look forward to your response on this matter.
 

Yours sincerely,

Lisa Smart MP