Lord Ashcroft yesterday tweeted: "Pleased to report my next book will be a biography of Carrie Johnson. She is an impressive person - a high-level career in politics and a record of campaigning on animal rights and the environment. Early research has proved fascinating."

       On the Conservative Home website, the peer said the book will examine Carrie's life and career before Downing Street.

       He said: "Many people know her as Boris Johnson's wife, but her influence developed long before she moved into 10 Downing Street, via her work over the last decade within the Conservative Party and also through the posts she has held working for ministers.

       "Aside from politics, she has campaigned in the fields of the environment and animal rights."

       Lord Ashcroft has previously published books on Rishi Sunak and Jacob Rees-Mogg, as well as a controversial David Cameron biography.