Labour has ratcheted up pressure on Boris Johnson over the £200,000 renovation of his Downing Street flat by calling on the Electoral Commission to launch an investigation into the funding.
Cat Smith, a shadow cabinet office minister, instructed solicitors at Edwards Duthie Shamash to write to the Electoral Commission.
In a letter sent by the legal firm and seen by the Guardian, the solicitors claim the prime minister committed a “prima facie breach” of the legislation regulating donations made to political parties and politicians.
They argue Johnson breached the Political Parties Elections & Referendums Act 2000, which requires a politician who receives a donation of more than £1,500 must report the gift within one month and provide the name and address of the donor.
Referring to Johnson’s register of interests maintained by the parliamentary commissioner for standards, the lawyers said: “As we understand it, no report has been made by him.”
They add that a £60,000 donation was made by Tory peer Lord Brownlow to help cover the shortfall considering a contribution from the Cabinet Office would be limited to £30,000, the legal firm said while alleging the donation did “not appear to have been reported to the Electoral Commission in the normal way”.
Earlier this month, Downing Street refused to deny reports that Johnson was considering setting up a charity to pay for the refurbishment of his official flat above No 11 Downing Street.
The lawyers argued that if Johnson was unaware of the identity of the donor, he was required by the same legislation to try to find out.
The lawyers wrote: “We are concerned that there appears to have been an attempt to conceal the true donor of the funds by arranging for the Conservative party to pay for the substantial part of the refurbishment.”
They added that it was “completely appropriate” for the Electoral Commission to begin investigating, and to demand that No 10 and Conservative party headquarters handed over documents to prove no wrongdoing.
The commission this month revealed that it had made preliminary enquiries to the Conservative party to discover how Johnson found £60,000 to pay for the renovations.
At the time, Allegra Stratton, the prime minister’s press secretary, said that “every twist and turn” of the refurbishment would be recorded, but added: “Conservative party funds are not being used to pay for any refurbishment of the Downing Street estate.”
The Electoral Commission, No 10 and CCHQ, did not respond to a request for comment.