Jennifer Arcuri is pursuing a "vendetta" against Boris Johnson, friends of the British Prime Minister alleged today, as Downing Street insisted he had done nothing wrong.
Johnson's affair with Arcuri has resurfaced after she gave a series of embarrassing interviews to a tabloid newspaper, including revealing details of text messages and even releasing a "selfie" photograph taken in his kitchen.
Arcuri, 36, claimed she had sex with Johnson, then London's mayor, on the sofa of the family home he shared with his now ex-wife Marina Wheeler in March 2016.
Arcuri also claims she sent him a topless photograph, which prompted Johnson to reply in a text message that it was "enough to make a bishop kick through a stained-glass window".
The affair, which began in 2012 and ended in 2016, is currently subject to an investigation by the Greater London Assembly's oversight committee over Johnson's failure to declare the relationship.
Arcuri, an American entrepreneur living in London at the time, was granted access to trade mission events and received funding from London & Partners, a company funded in part by the London mayor's office to promote the city.
However, today friends of Johnson questioned Arcuri's motives in telling her story to the Sunday Mirror and Daily Mirror four years after their affair ended. It is understood she has received a sizeable sum for an old-fashioned "kiss and tell".
An ally of the Prime Minister said: "There is no doubt in my mind that Boris is guilty of a monumental lapse in taste. At what point does the hawking of a story that is three years old cease to be news and start to look like a vendetta?"
Another friend suggested the relationship was only sporadic during those four years because Johnson was "too busy" to have a sustained affair while still married and working as London's mayor.
The friend questioned Arcuri's motive in taking the "selfie" in the kitchen and then keeping it, along with text messages, for years afterwards.
The friend said: "Is it really credible that Boris was rushing off for an afternoon bonk with this woman for four years? It seems incredible. I don't think it could be on the scale she is claiming.
"His aides knew where he was more or less the whole time. She [Arcuri] has obviously thought how she can maximise this for her own gain. You can't blame her, but she has saved that photo and texts for years and then just waited."
The prospect of an inquiry could push Johnson into the embarrassing position of having to defend his affair at a public hearing.
The Telegraph understands that the London Assembly committee will write to him, probably after the mayoral elections in May, asking why he did not declare his relationship, confidentially at least, which would have allowed him to keep the matter secret from his wife and family.
If the committee is unhappy with his written responses, it could demand that he gives evidence in public.
Sources said Arcuri's latest claims, made in the newspapers, were sufficient to trigger a new stage in the investigation.
Len Duvall, the chair of the oversight committee, said in a statement: "Our investigation will consider whether Boris Johnson conducted himself in a way that's expected from anyone in that position. It's important we get those answers, because Londoners deserve to have their politicians held accountable."
'No case to answer'
The Independent Office for Police Conduct (IOPC) said in 2020 that there would not be a criminal inquiry into whether "Mr Johnson used his position while Mayor of London to benefit and reward American businesswoman Jennifer Arcuri".
The IOPC said there was no evidence that Johnson had "influenced the payment of any sponsorship monies to Ms Arcuri" or that he had "influenced or played an active part in securing her participation in trade missions".
But the IOPC said that under the broader Nolan Principles of Public Life, "it would have been wise for Mr Johnson to have declared this as a conflict of interest, and a failure to do so could have constituted a breach of these broader principles".
Asked whether the Prime Minister would assist the GLA inquiry, his press secretary Allegra Stratton said: "He will engage, but this was already being looked at in detail by no less an authority than the Independent Office for Police Conduct.
"It found that these claims were untrue and unfounded. This was looked at in depth and it was found there was no case to answer.
"The Prime Minister follows the Nolan Principles in conducting himself in public life."
Stratton refused to say if he would give evidence in person if requested.
She added: "The work has been done, public time and money and effort has been spent looking into whether there has been any wrongdoing, and it was found that the Prime Minister, the then-London mayor, has no case to answer."
Another friend of Johnson's added: "Given all the stuff that was written before at a moment of heightened political interest ... you would have thought they would have been able to make it stick before.
"Does the general public really give a toss? It's not as though he's ever tried to be whiter than white."