Revealed: Furious Boris Johnson ‘threatens legal action’ over biography’s claims about Carrie

Boris Johnson spent hours in a state of fury in No 10 after claims about his wife were published in the serialisation of an unauthorised biography by a Tory peer – even threatening to take legal action, according to Downing Street insiders.

The prime minister claimed the book by Lord Ashcroft, which has been serialised in the Mail, was defamatory and told one worker he was getting advice from lawyers, The Independent understands.

Biography First Lady: Intrigue at the Court of Carrie and Boris Johnson alleges that Ms Johnson wields influence over her husband and, by extension, government decisions – though a spokesperson for Ms Johnson said she played no role in government.

The prime minister was focused on how to fight back against the negative press faced by his wife Carrie on Friday and over much of the weekend, sources claimed, describing him as “distracted and furious”.

This week one of the key pillars of the No 10 operation to get the Johnson premiership back on track, its plan to address the NHS backlog was not able to be unveiled on Monday as planned. Instead, the plan was published on Tuesday with reports suggesting it had been held up due to disagreements between No 10 and the Treasury over health service targets and funding.

Health secretary Sajid Javid denied that was the case, saying that it was instead delayed by efforts to get cross-Whitehall and NHS support for the drive.

The response to the reports about Ms Johnson’s influence over the prime minister has been mixed. Mr Javid is among those claiming the allegations in Lord Ashcroft’s book against Ms Johnson are sexist, telling Sky News on Monday that he thought “the partners of politicians should be off limits”.

It is rare for a sitting prime minister to issue legal proceedings. In 1993 Sir John Major successfully brought a libel case against satirical magazine Scallywag and the New Statesman over a report claiming he had had an affair with a member of No 11 catering staff. It later emerged that Sir John did have an affair, though it was with Edwina Currie, a fellow Conservative politician, in the 1980s.

In 2012, Mr Johnson used the services of legal firm Collyer Bristow to defend himself against a libel claim by union leader Bob Crow. Mr Johnson was successful in having the claim struck out.

When contacted for comment, No 10 said it was “completely untrue” legal action was being considered by the prime minister, who a spokesperson said was “entirely focused on delivering on the people’s priorities”. A spokesperson for Biteback, the publisher of Lord Ashcroft’s book, said of possible legal action: “That should help worldwide book sales and international publicity. All authors’ royalties are being donated to NHS charities.”