Boris Johnson described parts of his Downing Street flat as “a bit of a tip” as he solicited authorisation for renovations to his official residence, newly-disclosed messages to a Tory donor reveal.

The WhatsApp messages show the Prime Minister trying to hurry Conservative peer David Brownlow to give the go-ahead as he was “keen” for luxury interior designer Lulu Lytle to progress the work.

The “missing exchange” was previously not shared with ministerial interests advisor Lord Geidt as he investigated the funding of the works to No 11 that exceeded £112,500.

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But Lord Geidt became aware of the messages from November 2020 after reading an Electoral Commission report that fined the Conservatives last month for not following the law over the donations.

He published those messages on Thursday as he issued stark criticism of the affair, saying it “shook my confidence” because of the “real failures of process” in the saga.

On November 29 2020, the Prime Minister wrote: “Hi David I am afraid parts of our flat are still a bit of a tip and am keen to allow Lulu Lytle to get on with it. Can I possibly ask her to get in touch with you for approvals?”

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Later that day, Lord Brownlow replied: “Sorry for the delay I was out for a walk and didn’t have my ‘work’ phone with me. Of course, get Lulu to call me and we’ll get it sorted ASAP!”

He subsequently added: “I should have said, as the Trust isn’t set up yet (will be in January) approval is a doddle as it’s only me and I know where the £ will come from, so as soon as Lulu calls we can crack on.”

Mr Johnson had hoped that the trust would cover the refurbishments to the flat he shares with wife Carrie that exceed the £30,000 yearly allowance afforded to the Prime Minister.

Deputy Labour leader Angela Rayner said it was “a bit rich” for Mr Johnson to describe his official residence as “a bit of a tip”.