Boris Johnson has an outstanding court judgment for a debt of £535.

A search of the county court judgments database shows the “unsatisfied record” registered to the Prime Minister at “10 Downing Street”.

The date of the judgment, which was first revealed by the Private Eye magazine, is October 26 last year.

The official court records do not state who the creditor is, nor the nature of the debt.

The judgment was issued less than a fortnight after a Conservative donor told the party he was donating £58,000 to the party in relation to refurbishments at Mr Johnson’s Downing Street flat.

The Prime Minister has faced numerous questions about his finances as the Electoral Commission investigates whether any donation was properly declared.

Mr Johnson has denied any wrongdoing and insisted he personally paid for the lavish refurbishments, but has declined to say whether he received an initial loan.

Scrutiny intensified when former aide Dominic Cummings accused Mr Johnson of wanting donors to “secretly pay” for the renovations to the apartment in a “possibly illegal” move.

Tory peer Lord Brownlow said in an email leaked to the Daily Mail and dated October 14 that he was making a £58,000 donation to the Conservatives “to cover the payments the party has already made on behalf of the soon-to-be-formed ‘Downing Street Trust’”.

Mr Johnson is also under investigation by the Commons “sleaze” watchdog over his controversial new year break in the private island of Mustique.

The Parliamentary Commissioner for Standards Kathryn Stone is probing whether he properly declared the £15,000 stay on the luxury Caribbean hideaway.

Deputy Labour leader Angela Rayner said: “Another day, another report of deeply concerning irregularities about the renovation of Boris Johnson’s flat.

“This is not about Boris Johnson’s personal finances, the record speaks for itself that he has already broken the rules on declaring his financial interests, and he is already under investigation regarding potentially illegal wrongdoing.

“The issue of debt when it comes to the Prime Minister is whatever debt of gratitude Boris Johnson owes to the Tory donor who paid to renovate his flat, and what this donor or donors were promised or expected in return for their generosity.”

The Government’s website warns that bailiffs can be sent if judgments are not paid.

Banks and loan companies can also use the information to decide whether to issue credit or loans.

“If you’re late with your payments, you could be taken back to court and you may have to pay extra costs,” the website adds.

No 10 is yet to respond to a request for comment on the court judgment.