Dominic Cummings’ ex-aide Cleo Watson is writing a Downing Street bonkbuster

She might struggle to match the real-life dramas swirling around Downing Street at the moment, but a former No 10 insider is writing an erotic political thriller about salacious goings-on in Westminster.

Provisionally titled Whips!, the explicit novel is already being described as a cross between House Of Cards and 50 Shades Of Grey – and with characters said to be based on real-life political figures, it is being nervously awaited in Whitehall.

Its author is Cleo Watson, a protegee of Dominic Cummings, who was secretly writing the book while she was working for Boris Johnson. A friend of the 32-year-old said: ‘It is going to be very racy – soft-porn really. And it is likely to give the lawyers a lot of work.’

Cleo Watson and political advisor Dominic Cummings arrive at 10 Downing Street in 2019

Cleo Watson is a pivotal powerbroker who left Downing Street when Mr Cummings was ousted

Ms Watson, a pivotal powerbroker who left Downing Street when Mr Cummings was ousted in November, has told friends it will feature thinly disguised characters such as Sir Teddy Hammer, who will bear a striking resemblance to Sir Eddie Lister, Boris Johnson’s outgoing strategic adviser.

Whips! revolves around a young, female Commons researcher who is thrust into a dark, Machiavellian world of feuding and trysts after working on the successful party leadership campaign of a Tory MP.

For her part, Ms Watson worked alongside Mr Cummings on the Vote Leave campaign before entering government under Theresa May. She was frequently photographed arriving in Downing Street with a rather dishevelled Mr Cummings, a North London neighbour with whom she would share lifts.

A description in The Mail on Sunday of the pair looking like ‘a gazelle with a pit pony’ is understood to have left Mr Cummings ‘unamused’ – but Ms Watson’s nickname stuck.

After departing as Mr Johnson’s head of priorities and campaigns when Mr Cummings lost his power struggle with the Prime Minister’s girlfriend Carrie Symonds, Ms Watson now works as an adviser to Alok Sharma, president of the COP26 climate change summit.

While she has been creating fictionalised versions of her colleagues, Ms Watson will also be dramatised herself, as one of the characters in the forthcoming Downing Street TV drama This Sceptred Isle. Actress and model Greta Bellamacina has been cast to play her.

Its author is Cleo Watson, a protegee of Dominic Cummings, who was secretly writing the book while she was working for Boris Johnson 

After departing as Mr Johnson’s head of priorities and campaigns when Mr Cummings lost his power struggle with the Prime Minister’s girlfriend Carrie Symonds, Ms Watson now works as an adviser to Alok Sharma (pictured)

Cleo, who recently married a financier called Tom, is one of five sisters and is neither the first to go into politics – nor into middle-class erotic fiction. Her eldest sibling, 42-year-old Annabel, known as Bee, was Mrs May’s chief of staff, while Molly wrote a racy chronicle of the horsey set in Ledbury, Herefordshire… with Bee as one of the characters.

In The Pink recounted the escapades of two sisters who ‘abandoned their careers in London to follow their dreams of a sunny rural idyll’ and were ‘thrown into a hair-raising world where the horses have cocaine habits and the locals have developed their own alternative to Viagra’.

One passage says of Bee: ‘As she stands, whip in hand, her bottom and thighs showcased by skintight white jodhpurs rising out of spurred boots, she looks at once wanton, but also proper to the point of being prim.’

The Watson sisters – Cleo, Bee, Molly, Nell and Flora – enjoyed an idyllic childhood in a 400-year-old mansion in the Brecon Beacons, and were educated at the £30,000-a-year Haberdashers Monmouth girls’ boarding school, where Nell, now 35, was head girl. Flora, 39, is a talented gift designer.

Their grandfather, Vice Admiral Sir Dymock Watson, was a Second World War veteran who later commanded the aircraft carrier HMS Illustrious before being put in charge of British naval forces in the South Atlantic. In the 1950s, he bought Trebinshun House, where the girls and their brother Archie were raised.

Last night, one of Ms Watson’s friends said: ‘Whips! will be a lot more explicit than Molly’s book – there will be plenty of action for honourable members.

‘Cleo will be drawing on all of the stories she has heard about sex and skulduggery during her career – it’s an erotically charged The Thick Of It.’