As a man facing claims of sleaze, the last thing Boris Johnson needs is for a former aide to write a “soft porn” novel lifting the lid on sex and scandal in Downing Street.

Whips!, by Cleo Watson, a close ally of Dominic Cummings, is described as “a cross between House of Cards, The Thick of It and 50 Shades of Grey”.

Watson, 32, a statuesque figure dubbed “the Gazelle” by some, left Downing Street this year after helping to organize the Cop26 climate talks. Friends say she has been spending her weekends penning the work of “erotic literature”, featuring sex scenes that are “a pretty decent notch up from Jilly Cooper”. The book is likely to be studied by Westminster-watchers seeking to identify the oversexed ministers, MPs, special advisers and journalists portrayed.

A friend of Watson said: “It’s a work of fiction but it is heavily drawn from Cleo’s own experiences and stories from the whips’ office and urban legends around Westminster. There will be jokes about putting honorable members in dispatch boxes but there will also be some pretty explicit scenes in there as well.”

One character who bears more than a passing resemblance to a former Downing Street aide is named Teddy Hammer. While a fictional facsimile of Johnson is unlikely to be a central character, some of his “choice quotes and stories” are expected to find their way into the mouths of the characters. Johnson is aware of the project. At Watson’s leaving drinks, he is understood to have said: “Government’s loss will be erotic literature’s gain.”

Watson worked with Cummings at Vote Leave and became his right-hand woman in Downing Street. But he is unlikely to be a focus of the erotica. “There will be some Dom-isms in there, but I don’t think particularly in the sex scenes. Dom is not a chick-lit sex object,” the friend said.

“Government’s loss will be erotic literature’s gain.”

The book is to be the first in a trilogy chronicling the rise and fall of advisers, MPs, ministers and prime ministers and is due to be handed in to her publisher next year.

One of Watson’s four sisters, Molly, wrote In the Pink about the horse-riding set in the Brecon Beacons, where they grew up. Another sister, Bee Roycroft, was an aide to Theresa May.

Watson’s book “will poke fun at everybody”, one of her friends said. “It will lift the lid on just how farcical it can be sometimes.”

Johnson also penned an explicit novel about terrorism, called Seventy-Two Virgins: A Comedy of Errors, which featured a bicycling MP who was having an affair. It features women variously described as being “a mega-titted six-footer” and having “lustrous eyes”, “long legs”, and an “unambiguously exuberant bosom”.

Tim Shipman is the political editor of The Sunday Times of London. He is the author of All Out War: The Full Story of How Brexit Sank Britain’s Political Class and Fall Out: A Year of Political Mayhem