Parliament’s sleaze watchdog must investigate Prime Minister Boris Johnson over the funding of the lavish refurbishments to his Downing Street flat, Labour has urged.

Deputy leader Angela Rayner called for the Commissioner for Standards to probe whether he broke parliamentary rules by not declaring any donation in the MPs’ register of interests.

The adviser on ministers’ interests appointed by Mr Johnson cleared him of breaching the ministerial code but said he had acted “unwisely” over the work.

Now Labour wants the standards commissioner in the Commons, Kathryn Stone, to investigate a potential breach of the MPs’ code of conduct.

Deputy Labour leader Angela Rayner
Deputy Labour leader Angela Rayner (Jacob King/PA)

Downing Street said support relating to ministerial activity should be declared on the ministers’ register, as has been done.

But in a letter to the commissioner, Ms Rayner noted she has previously reprimanded Mr Johnson, including in 2019 when he was warned any further breaches may warrant “more serious sanction”.

“It appears that, far from learning the lessons of his previous transgressions, the Prime Minister has continued with his attitude of treating basic standards of integrity, openness and transparency with contempt and behaving as though there is one rule for him and another for everyone else,” Ms Rayner wrote.

“I therefore write to request that you instigate a further investigation into the Prime Minister’s failure to register this donation, using your powers as commissioner.”

She also accused Mr Johnson of breaching the general principles on conduct in public life of “selflessness, integrity, objectivity, accountability, openness, honesty and leadership”.

The Prime Minister can use an annual public grant of up to £30,000 to decorate his Downing Street home, but renovations at No 11 reportedly spiralled up to £200,000.

Lord Geidt, the adviser on ministers’ interests, found Mr Johnson had not been aware Tory donor Lord Brownlow initially had settled an invoice for the works.

But Lord Geidt said Mr Johnson acted “unwisely” in allowing the refurbishment to go ahead without “more rigorous regard for how this would be funded”.

Prime Minister Boris Johnson and his wife Carrie
Prime Minister Boris Johnson and his wife Carrie (Stefan Rousseau/PA)

Ms Stone is already investigating whether Mr Johnson properly declared a £15,000 holiday on the Caribbean island of Mustique with his wife Carrie.

A Downing Street spokeswoman said: “Lord Geidt’s independent report shows the Prime Minister acted in accordance with the ministerial code at all times and sets out the background to the intended establishment of a Downing Street trust.

“The report shows how, at all times, the Prime Minister followed the advice of officials and he has made a declaration in his list of ministerial interests, as advised by Lord Geidt.

“The House of Commons rules and Electoral Commission guidance are clear that support relating to ministerial activity should be declared through ministerial declarations and this has been done.”

In April, Labour backbencher Margaret Hodge also called for Ms Stone to investigate.

The former chair of the Commons Public Accounts Committee said Mr Johnson had “repeatedly failed to be honest, open or transparent” about the donations and gifts he receives.