WESTMINSTER’S "sleaze" watchdog has announced it will not investigate Boris Johnson over the £112,000 refurbishment of his Downing Street flat.

Parliamentary Commissioner for Standards Kathryn Stone had faced calls to investigate whether the Prime Minister broke the rules for MPs after his adviser on ministerial interests, Lord Geidt, revealed last week that Johnson had failed to tell him about exchanges with a Tory donor who helped fund the revamp.

Opposition leaders called on Stone to open an inquiry after it emerged that the Prime Minister had discussed a pet project by Lord Brownlow for a “Great Exhibition 2.0” in WhatsApp messages in which he also asked for the go-ahead for the refurbishment work.

Ministerial records show that, six weeks later, Lord Brownlow met then-culture secretary Oliver Dowden and representatives of the Albert Hall to discuss his proposal – although it did not in the end proceed.

Labour say it was “corruption plain and simple” if Lord Brownlow was able to get access to ministers in return for helping to bankroll the redecoration work.

The National:

READ MORE: Boris Johnson complained that his Downing Street flat is a 'bit of a tip'

However the Prime Minister’s official spokesperson said it had been confirmed that Stone would not be carrying out an inquiry into the matter.

“It is not for me to speak on behalf of her, but I understand she has confirmed they won’t be looking at that,” the spokesman said.

It is understood that Stone wrote to No 10 at the end of last week, making clear that support for ministers in their ministerial activities should be declared through the Ministerial Code – which Johnson did – rather than the Register of Members’ Interests, which she polices.

In his report last week, Lord Geidt said he would not have changed his original conclusion that Johnson did not breach the Ministerial Code if he had been aware of the exchanges with Lord Brownlow, although he made clear his deep unhappiness at the way the issue had been handled.

The Prime Minister said after he learned that the work – which far exceeded the official £30,000 allowance – had been paid for by the Conservative Party, including a donation by Lord Brownlow, he reimbursed the costs from his own pocket.

A previous investigation by the Electoral Commission resulted in the party being fined £17,800 for failing to properly declare a £67,000 donation from a firm controlled by Lord Brownlow.