A county court judgment against Boris Johnson for a debt of £535 was issued over a claim of defamation, it has emerged.

Downing Street said the debt claim against the Prime Minister was “totally without merit” and “vexatious” as an application was being lodged in an attempt to strike it out.

Official records showed an “unsatisfied record” for the unpaid debt was registered to Mr Johnson at “10 Downing Street”, with the judgment dated October 26 last year.

An additional file shows the claim was made by a claimant named Yvonne Hobbs against “The Rt Hon Boris Johnson”.

The reasons cited for the claim were “defamation” and “committed repeated defamation”.

I can confirm it is nothing to do with the refurbishment of the Downing Street estate, where all such bills have been duly paid either by the Government or the Prime Minister personally

The Prime Minister’s official spokesman told a Westminster briefing: “We are moving at speed to get this removed.

“Courts do have the power to strike down vexatious claims as an abuse of the court, and they do issue various orders restricting litigants’ ability to continue with further claims.”

The judgment, first reported by Private Eye magazine, raised eyebrows as it was dated during a key period concerning questions over the Prime Minister’s controversial refurbishment of his flat in No 11.

Downing Street earlier appeared unaware of the judgment but officials insisted it is not linked to the flat renovation, which the Electoral Commission is investigating to ascertain whether any donations were properly declared.

“I have seen that report, we are looking into this issue,” the Prime Minister’s official spokesman said.

“I can confirm it is nothing to do with the refurbishment of the Downing Street estate, where all such bills have been duly paid either by the Government or the Prime Minister personally.”

The judgment was issued in the county court at the Online Civil Money Claims service.

The Government website says: “If you get a judgment, this means that the court has formally decided that you owe the money.”