Boris Johnson told ‘months ago’ peerage for Nadine Dorries had been rejected

Former PM told by Cabinet Office she was not on the list of approved nominations as early as February

Boris Johnson was told his attempt to award a peerage to Nadine Dorries had been rejected as long ago as February, senior government sources have made clear.

The former prime minister and his close political ally stunned Westminster when they announced they were quitting as MPs on Friday, triggering by-elections the Conservatives, currently struggling in the polls, could lose.

They are now both locked in a public spat with Rishi Sunak over her peerage, amid claims Mr Johnson did not know until recently some of his nominations had been omitted.

Ms Dorries has accused the prime minister of “duplicitously and cruelly” blocking her appointment and claimed that information needed for her to pass the vetting process was held back.

She has also said she discovered her name was not on the list half an hour before it was published.

But the government disputed her claims.

It is understood that Mr Johnson was told she was not on the list of approved nominations as early as February. That was when the prime minister was informed who had been successfully vetted by the House of Lords Appointments Commission (Holac).

The information is thought to have been relayed to Mr Johnson by the government’s Cabinet Office. The update came weeks before the two men discussed the list when they met earlier this month – and well before Ms Dorries says she was informed.

On Monday the growing tensions over the peerages row spilled over as Mr Sunak publicly said his one-time ally had asked him to “do something I wasn't prepared to do”.

The prime minister suggested Mr Johnson wanted him to ignore the Holac recommendations.

But Mr Johnson’s camp accused the PM of having “secretly blocked” peerages, including that of Ms Dorries and other loyalists.

In an extraordinary statement, Mr Johnson hit out at his successor saying: “Rishi Sunak is talking rubbish.

“To honour these peerages it was not necessary to overrule Holac – but simply to ask them to renew their vetting, which was a mere formality.”

The Cabinet Office dismissed the attack, saying: “Holac did not support the nominations of the MPs put forward by the former prime minister. It is unprecedented for a sitting prime minister to invite Holac to reconsider the vetting of individual nominees on a former prime minister's resignation list. It is, therefore, not a formality.”

Downing Street said it would have been inappropriate for either No 10 or the Cabinet Office to contact individuals going through the vetting process directly.

“In line with the longstanding custom, the prime minister forwards the list unaltered following vetting by Holac,” the prime minister's official spokesman said.

“Obviously, it is not for No 10 or the Cabinet Office to be in contact with individuals going through the Holac process – again, that would not be appropriate.”

Mr Sunak also hit back at a claim Ms Dorries that a “class ceiling” blocked her elevation to the Lords.

She branded Mr Sunak and his close aide James Forsyth as “privileged posh boys”.

Asked if Mr Sunak thought only posh boys should go to the Lords, the prime minister’s official spokesman replied: “No.”

As the Tory infighting continued for a fifth consecutive day, Sir Keir Starmer accused Boris Johnson of throwing a “political tantrum”.

The Labour leader described the situation as “really unprecedented” and said parties “usually fight like this when they are out of office”.

A spokesman for Mr Johnson has been approached for comment