Full details of how Boris Johnson’s Downing Street flat refurbishment was funded should be published, Labour has demanded.

The ministerial sleaze watchdog appointed by the Prime Minister said Mr Johnson “unwisely” allowed the work on the apartment to go ahead without “more rigorous regard for how this would be funded”, but cleared him of breaking the rules.

Deputy Labour leader Angela Rayner has written to Lord Geidt, the independent adviser on ministers’ interests, questioning how he reached his decision and calling for full transparency about the renovations.

The PM can use an annual public grant of up to £30,000 to decorate his Downing Street home, but it has been reported that the renovations at No 11, where Mr Johnson lives with his fiancee Carrie Symonds, reached up to £200,000.

There had been discussions about a Downing Street Trust being set up to pay for the work, before legal advice received in June 2020 “raised doubts” about whether such a body “would be capable of dealing with costs associated with the private residences”, said the adviser.

But Lord Geidt found Mr Johnson had not been aware that in lieu of any such trust to fund the refurbishment being set up, Tory donor Lord Brownlow had settled the bill.

In her letter to Lord Geidt, Ms Rayner said it appears the details have not been published because they are “no longer current”, but the only explanations for that are because the Prime Minister did not declare it and the lengthy delay in publishing the list of ministers’ interests.

She told Lord Geidt: “This cannot therefore be used as a justification to not publish this interest.

“Will you now publish this interest, all the details relating to this interest and these payments, and any correspondence related to this interest and these payments immediately?

“The public cannot have faith in the system of registering and declaring ministerial interests when these interests, debts and payments have still not been declared.”

Questioning how no potential conflict of interest had been found, she said the public would “legitimately and reasonably assume that the Prime Minister – or indeed anybody – becoming indebted by a sum of tens or even hundreds of thousands of pounds would, or could at least be perceived, to have an obligation to the individual or institution doing them a financial favour”.

She added that it is “staggering” and “frankly scarcely believable that the Prime Minister apparently had no idea about who was funding work that cost tens or even thousands of pounds”.

Ms Rayner said: “I am certain that there will be nobody else in the country who will have had building work carried out in their residence and not know, or even seek to find out, who was paying for it.”

Lord Geidt’s report said that by the late autumn of 2020, it was apparent establishing a new trust was still likely to be many months off and in October Lord Brownlow told Cabinet Office officials he had settled an invoice for the works on the flat directly with the supplier.

Lord Geidt said “the Prime Minister, unwisely, in my view, allowed the refurbishment of the apartment at No 11 Downing Street to proceed without more rigorous regard for how this would be funded”.

But he said the PM knew “nothing about” payments for the refurbishment work, which started while he was in hospital with coronavirus, until reports in the media surfaced in February 2021.

“At that point, the Prime Minister immediately sought the necessary advice about his interests and, as a consequence, settled the full amount himself on March 8 2021.”