Jennifer Arcuri has reportedly admitted having an affair with Boris Johnson months after he faced allegations of using his position as mayor of London to get the US businesswoman favourable treatment.
The prime minister was formally referred to the police watchdog last year over the awarding of public money and trade trips attended by Ms Arcuri while he was at City Hall between 2008 and 2016.
Following a nine-month inquiry the Independent Office for Police Conduct (IOPC) found no evidence Mr Johnson influenced the payment of thousands of pounds to the US businesswoman and said it would not launch a criminal investigation.
However, it found that the prime minister would have been “wise” to declare a conflict of interest and said failure to do so could have constituted a breach of the so-called Nolan principles on conduct expected from public servants, which include integrity, selflessness, openness and honesty.
The watchdog also said it was unable to determine the nature of Mr Johnson’s relationship with Ms Arcuri, but said there was a “close association” between the pair which “may have been intimate” during the relevant period.
According to an interview with the Daily Mail on Saturday, when asked if she had had an affair with then-mayor of London, Ms Arcuri replied: “I think that goes without saying… It’s pretty much out there… But I’m not going to talk about it.”
At the time, Mr Johnson was married to Mariana Wheeler, who he has four children with, but the couple have since divorced and the prime minister is now engaged to Carrie Symonds, a former director of communications at the Conservative party.
Addressing the issue in May, a spokesperson for the prime minister said: “We welcome the fact that this politically motivated complaint has been thrown out. Such vexatious claims of impropriety in office were untrue and unfounded.
“An independent review by the government Internal Audit Agency similarly showed the claims made by the Labour Party were false. This was not a policing matter, and we consider this was a waste of police time”.
IPOC director general Michael Lockwood also said in a statement: “The IOPC completed a thorough, independent and impartial assessment to determine if there were reasonable grounds to suspect the criminal offence of misconduct in public office had occurred.
“We found no evidence to indicate that Mr Johnson influenced the payment of any sponsorship monies to Ms Arcuri or that he influenced or played an active part in securing her participation in trade missions.”
But he added: “There was evidence to suggest that those officers making decisions about sponsorship monies and attendance on trade missions thought that there was a close relationship between Mr Johnson and Ms Arcuri, and this influenced their decision-making.”