Police decline to investigate Boris Johnson's use of a government jet in the Hartlepool by-election, say law wasn't broken

• Cleveland Police said they will not investigate Boris Johnson's use of a government jet.
• Johnson flew with taxpayers' money to campaign in the Hartlepool by-election.
• The trip could have breached election-spending laws, but the police said Thursday it did not.

Police in the UK will not formally investigate Boris Johnson's use of a government jet to campaign in the Hartlepool by-election, Insider can reveal.

Instead, officers said Thursday that the trip did not appear to breach any laws, seeming to bring their involvement to an end.

An investigation by Insider into the Conservative Party's campaign in the by-election found Boris Johnson used a taxpayer-funded government jet to travel from London to Teesside for a mixture of an official visit and political campaigning.

Official rules say transport for mixed purposes should be jointly paid for by the government and the party. A copy of the Conservative Party's spending return for the by-election said it declared £0 in expenditure on transport, suggesting it had not covered the flight.

Photographs taken that day of Johnson with the Conservative candidate for Hartlepool, Jill Mortimer, were used in Conservative campaigning material. The Conservatives went on to win the contest.

Downing Street and Conservative Campaign Headquarters (CCHQ) repeatedly denied any wrongdoing.

A spokesperson for Cleveland Police told Insider: "We received an allegation of potential breaches of the Representation of the People Act. These are automatically referred to the Crown Prosecution Service Special Crime Division to advise on the next steps to take.

"Requests for information were sent to third parties and this information has now been reviewed. In consultation with the CPS, it has been ascertained that there were no breaches of the Act. Third parties have been informed of the outcome."

Johnson's standards advisor also refused to investigate, or to disclose whether he spoke to Johnson about the matter.

Lord Geidt, the Prime Minister's independent adviser on ministers' interests, said that he does "not consider this to be a matter requiring my advice".

In the months since, Johnson has been dogged by more claims of the mishandling of money. On Thursday, the Conservatives were fined £17,800 by the Electoral Commission over the inappropriate declaration of donations used to renovate Johnson's flat in 10 Downing Street.