Want to know all about the sex and skulduggery in Westminster?

Boris Johnson’s former adviser Cleo Watson knows better than most what goes on in the corridors of power at Westminster.

Working at No 10, firstly with Theresa May and then with Johnson, opened her eyes to the daily drama at the heart of government, offering her a bird’s eye view of absolutely everything which goes on behind closed doors, as well as in front of the cameras.

Unsurprisingly, there’s been a buzz around her debut novel, Whips, a sexy romp set in the run-up to a party leadership race, in the vein of Jilly Cooper but set in the world of politics – and featuring all the bravado and back-stabbing which goes with it.

It centres on three friends from university who try to make their way in the Westminster bubble. Bobby is a researcher for a Tory MP, Jess is a political journalist and Eva (like Watson was) is a government adviser.

Within the first few pages, a randy female minister of state is having desk sex in a Westminster office with an accommodating companion, who witheringly suggests she stops texting while they’re in the act. It’s reminiscent of Jackie Collins, but with the chimes of Big Ben echoing in the background.

“There’s plenty of opportunity for it to happen, partly because of the way the buildings are designed, partly because you have party conferences and summer parties and late votes, where people are drinking wine with each other.”

Watson, 34, Johnson’s former co-deputy chief of staff, explains that she just wanted to have fun, to produce a satire that went beyond reality, with strong women at the heart of the piece.

The author stresses that this is a work of fiction, but there are some pretty familiar characters. Percy Cross, for example, is an ex-prime minister who resigned in disgrace and is bumbling, charismatic and gaffe-prone, spending his time writing biographies of his favourite historical figures.

“The Percy character is pretty obviously Boris Johnson now, but when I wrote him everyone was saying, ’10 more years of Boris’. I’ve written his current life two years in advance,” she says wryly.

She recently wrote in Tatler that she was ‘closer to being Boris’s nanny’ at No 10 during the pandemic, when she would have to take his temperature regularly and check he was washing his hands.

Today, she recalls: “After he came out of ICU [when he had Covid] he obviously wasn’t feeling well, but constitutionally the way the Government works is that he couldn’t take sick leave. It required people managing his time and schedule, so he could rest and eat right.

“Some of it was the practicalities of getting him back in shape. I didn’t set out to do what I called the nannying role, it’s just what I found he responded to. Bearing in mind that a lot of his time was spent having frank, fairly aggressive male-dominated conversations, I found that to get him to do stuff and to get out of him what was needed, chiding and mollycoddling was what he responded to.”

She says of the former prime minister: “I think he’s as complicated as the rest of us, if not more so. He has the kind of motivations that are punishing in their own way. I don’t know when he feels peaceful.

“He was fun to work for, could be interesting, but obviously very frustrating as well, and inconsistent. Having worked for him and Theresa May, you couldn’t work for people more different, with different strengths and weaknesses.”

In her fiction she paints the outgoing PM, Madeleine Ford, who her colleagues are ganging up against – mostly behind her back – as a more sympathetic character who remains steadfast and honourable despite it all. Watson admits that it was difficult not to write her without alluding to Theresa May.

“I don’t know how much of that is a reaction to when I was working with her [as junior political adviser in 2017] when she was working so hard. She had the worst kind of parliamentary arithmetic. I thought she was a really nice person and was misunderstood in the media.

“She had a lot of quite aggressive sexist media written about her, but also her own MPs saying terrible things in public.

“At various points, whoever’s in charge, there are jealous people keen to take over, unhappy with the ways things are going. But it felt like the jeopardy was stronger. She was saddled with getting Brexit done. It felt more vicious because I could see she was working herself to the bone behind the scenes.”

When May decided to step down, things felt quite peaceful for a while, Watson recalls.

“She had time to say goodbye to people, having short meetings with each adviser individually to say thank you for [their] work. I don’t think anyone’s had that before.” It’s no surprise that May was at Watson’s recent book launch in central London.

After May left No 10, Watson was asked by Dominic Cummings – who was at university with one of her sisters and who she’d met a few times – to join him as co-adviser to Johnson. It led to higher media scrutiny, which she found difficult, although her friends and family were able to separate her political profile from her private life, she recalls.

She left Downing Street in November 2020, two weeks after Cummings, then helped with the Cop26 climate summit, but by the end of 2021 was pursuing full-time writing. She keeps in touch with Cummings but not with Johnson.

Will readers recognise other politicians in the novel? “I’m amazed how many characters people seem to think are based on Matt Hancock,” she observes. “Some people see him as a slightly dark person and some as just a bit hopeless. So he’s been a combination of people.”

As one of six children, Watson grew up in south Wales, where her parents ran a business language school. She studied politics and economics at Cardiff University, and was given the chance to spend a year in the US, where she worked on President Obama’s 2012 re-election campaign.

Returning home, she worked on the Vote Leave referendum campaign.

“Truthfully, like many people in their 20s, I didn’t have a particular position on the European Union. But I wanted to work in campaigning. And the campaign that looked like you’d have a better chance of having a seat at the table was the Leave one, because everybody was piling in on the Remain one.

“I was ambitious and wanted to work in campaigns. I honestly didn’t think we would win. But once we did win, I thought, OK, I now feel like this has to be a success.”

She then clinched a job in Theresa May’s political office during the Tory general election campaign.

Today, she lives in London with her barrister husband, Tom Haggie, and would eventually like to return to south Wales. She’ll continue with writing and there’s a sequel in the offing.

She’s not big on social media, but recently joined Twitter for book purposes. “I don’t like peeking behind the curtain at politics on Twitter. I think for lots of people, politics isn’t just a job, it’s a real vocation, a huge part of who they are.

“Some people, when they leave politics, still have an itch left to scratch. I’m scratched down to the bone.”

Whips, by Cleo Watson, is published by Corsair, priced £20. Available now