Isabel Oakeshott has has said her relationship with Matt Hancock soured after he abandoned her in the middle of writing their book in order to appear on I’m a Celebrity.

As she faced ethical questions over her decision to breach her non-disclosure agreement with Hancock and take his WhatsApp messages to the Daily Telegraph, Oakeshott said she chose the newspaper for ideological reasons, because it “pushed back against lockdown during the pandemic”.

She told the Guardian she had spent last year pouring all her energy into co-writing Hancock’s pandemic diaries, only for him to vanish while arguing with the government over what they could publish.

“I didn’t think about any further pandemic-related project until after publication of Matt’s book in December. That process had been utterly all-consuming, especially since he vanished to the jungle at a critical moment in very difficult dealings with the Cabinet Office. He didn’t tell me he was going,” she said.

Rumours that the Telegraph was working on a top-secret project, with a special team of reporters seconded from the main newsroom, had been circulating in journalism circles for weeks. But the revelation that the story was a leak of Hancock’s private WhatsApp messages took staff at rival newspapers – and especially Hancock – by surprise.

This was felt especially keenly at Rupert Murdoch’s News UK, where Oakeshott enjoys a generous salary to be international editor and appear as a regular pundit on its talkTV channel. On Wednesday night, the TalkTV presenter Tom Newton Dunn said the Sun’s political editor, Harry Cole, had had a “bit of a dust-up” with Oakeshott outside the studio.

Cole said: “I just think it’s a dubious choice of newspaper, a rival news organisation getting all the glory.”

Newton Dunn asked: “You’d prefer she go to the Sun?”

Cole then listed various News UK-owned publications: “The Sun, Times, Sunday Times, other vessels are available in the building.”

For her part, Oakeshott has made clear she is employed on a freelance basis by News UK’s television channel and is free to work for other newspapers.

She said she took the WhatsApp messages to the Telegraph because of its opposition to lockdowns. “The story simply did not fit with the editorial stance of any News UK paper. None of these brilliant titles pushed back against lockdown during the pandemic.”

Exactly when Oakeshott passed the messages to the Telegraph is less clear, although the prominent lockdown sceptic says she did not decide to ghostwrite a book by the pro-lockdown Hancock with the intention of leaking his private messages.

In December, the pair launched their book at the Science Museum, posing together for the press. Weeks later, a team at the Telegraph were starting to scour the WhatsApp archive for embarrassing revelations.

The lockdown files are catnip to her employers at TalkTV, where presenters and guests have been consistently critical of Hancock and the government’s lockdown policies during the pandemic. As a result, TalkTV has featured Oakeshott heavily for the last 24 hours, including in appearances on the primetime Piers Morgan show, the breakfast show with Julia Hartley-Bewer, and on Mike Graham’s mid-morning slot.

Graham said while introducing Oakeshott: “The world is a different place to where it was a couple of days ago, because in the last two days an incredible story has emerged thanks to Isabel Oakeshott, TalkTV’s international editor. If it wasn’t for her, this wouldn’t be happening. So let’s just remember that.”

The only issue is that News UK has not had any of the raw information. For that, people would have to buy a subscription to the Telegraph, a direct competitor to the paywalled Times.

While Oakeshott has publicly praised the Sunday Times, in recent years she has had a strained relationship with the outlet where she once worked as political editor. In 2019, the newspaper revealed she was in a relationship with the Brexit party founder Richard Tice, as part of a story questioning how Oakeshott had obtained leaked memos that took down the UK’s ambassador to the US. This led to Oakeshott and Tice unsuccessfully complaining to the press regulator Ipso about a breach of privacy.

Staff at the Telegraph are cock-a-hoop at the story and its success, while Oakeshott has toured studios justifying her decision to leak as being in the public interest. On TalkTV, she singled out the Guardian and criticised “columnists wanging on about journalistic ethics”.

She said: “There’s so much complaining about journalistic ethics, which always seem to come from people who have never had a story big enough to present them with any journalistic ethical dilemma. I make no apology whatsoever for acting in the public interest on this.”

Oakeshott insisted she did not sell the messages to the Telegraph but was employed to work on the project as a reporter. “I’m a working journalist,” she told BBC Radio 4’s Today programme. “They did not pay me for the messages. I’ve been helping the Daily Telegraph with the investigation.”

She added: “Anyone who thinks I did this for money must be utterly insane. This is about the millions of people – every one of us in this country – that were adversely affected by the catastrophic decisions to lock down repeatedly, often on the flimsiest of evidence, for political reasons.”