SIR Keir Starmer ignored advice to do security checks on Peter Mandelson before announcing him as US ambassador, documents show.
The PM was told by then-civil service chief Simon Case to make sure the Labour peer passed his vetting before publicly making the appointment.
Lord Mandelson would go on to fail his security vetting but was given clearance anyway by Foreign Office boss Sir Olly Robbins.
Sir Keir has said this was “unforgiveable” and last week sacked Sir Olly from his post for keeping this information from him.
He will claim in a make-or-break Commons statement today that he was disgracefully kept in the dark that Lord Mandelson had failed vetting.
But hours before he was due to face MPs, documents resurfaced that show he was advised to make sure the vetting had been completed ahead of announcing the ambassador job.
Ahead of hiring the Labour peer, then Cabinet Secretary Lord Case told the PM: “You should give us the name of the person you would like to appoint and we will develop a plan for them to acquire the necessary security clearances and do due diligence on any potential Conflicts of Interest or other issues of which you should be aware before confirming your choice.”
It raises questions over why Sir Keir did not wait for the vetting to be done before announcing Lord Mandelson to the public as his man in Washington.
It could lead critics to claim Sir Olly felt pressured into signing off Lord Mandelson’s security clearance because the PM had already made up his mind.
The axed Foreign Office chief will give his own evidence to MPs tomorrow to set out his version of events.
It comes as Sir Keir will face MPs over the Peter Mandelson vetting scandal in a crunch Commons showdown today.
The PM was told to ditch the evasion as he fights to bring his premiership back from the brink after being kept in the dark about ex-Labour grandee Mandelson’s security status.
Sir Keir is under huge pressure over a slew of policy U-turns, dismal poll ratings and calls for him to resign — but allies have told wannabe leadership challengers to put the country first.
The Prime Minister will insist he was not told that Peter Mandelson failed the vetting for the top diplomatic post in Washington, and will turn his fire on the Foreign Office.
In a battle once again to secure his premiership, Starmer will say that the now sacked Robbins overruled the vetting decision without the authority to do so.
However, Starmer was urged to tell “the truth, the whole truth and nothing but the truth” over the scandal by the Tories last night.
In a blistering attack, Tory leader Kemi Badenoch said: “I will be seeking answers to questions to which the British people will rightfully expect complete and truthful responses.
“No more evasion. No more digressions. Parliament and the public will want to hear you give us the truth, the whole truth and nothing but the truth.”
Ms Badenoch has written to the PM calling for full transparency and accountability, claiming there has been a series of inaccuracies in his public statements.
The PM, who said he did not learn about the failed vetting until Tuesday last week, had previously said that “due process” was followed over the appointment to the Washington DC-based post.
He will also be asked to explain the repeated requests made by No 10 to the Foreign Office about assurances over Mandelson’s suitability for the coveted role.
The Opposition is also furious that the PM did not go to the House of Commons as early as possible to correct the record.
Senior government sources have claimed it was Mandelson’s foreign links that led to a recommendation against his appointment, rather than his friendship with paedophile financier Jeffrey Epstein.
Mandelson was sacked last year less than 12 months after he was appointed when details emerged of his ties with Epstein.
It was revealed last week that he was not granted developed vetting status during the appointment process but this was overturned by Sir Olly, who did not tell No 10.
However, No 10 believes he had the opportunity to raise the report on four different occasions.
It says it could have been disclosed when he saw the advice or when Mandelson was sacked.
Insiders revealed he could have also raised the issue when the Government was forced to release material on the appointment and also when ministers said they would review security vetting last month.
But he was not stopped by law from “sensibly flagging” recommendations from the vetting body regarding Mandelson’s appointment, a Government document reveals.
Paperwork released last night says there is “nothing in the guidance” that prevented details being shared in the Mandelson scenario.
The law states that civil servants make decisions on vetting and clearance but they can raise recommendations to ministers to make judgments, appointments or even explaining matters to Parliament.
It states that this could have been done in a “proportionate and necessary way” if in line with the appropriate steps.
