George Downing was one of the English Civil War's most cunning spies. As Oliver Cromwell's head of military intelligence, he forged a career as a politician and diplomat, bribing, blackmailing and browbeating his way to success, before spectacularly betraying his friends by defecting to the Royalist camp.

Always close to the action, Downing walked with the most illustrious men of his times: Oliver Cromwell and Charles II were his patrons; Samuel Pepys was his clerk; William of Orange godfather to his son. And when he came to build his famous street, Downing Street, which became the home of Britain's prime ministers, his surveyor was Sir Christopher Wren.

Downing helped start two major wars and had a hand in founding New York. Yet he has remained an elusive figure in history, as if hiding himself in footnotes. Turncoat tells the full story of Downing's espionage and double-dealing for the first time, following this mystery man from the asceticism of Puritan New England, across battlefields and through courts, chancelleries and parliaments, to the heart of wealth and power in Restoration London.

"Succeeds in bringing Downing out of the shadows and evoking his "convulsive" times... The best bits are when we can hear Downing's voice from his letters, chilling battle reports, or quips in parliament." - Observer

"Lively and engaging... Turncoat not only illuminates the shadowy world of 17th-century spycraft, it also traces the social, religious, and political networks that propelled Downing from his humble beginnings to positions of power." - History Today

"What we get from this well-researched book is a fascinating insight into one of the most violent and troubles eras of Britain's past and a survival manual for how to get by without losing your head." - Mail on Sunday

"Sewell scores well in his command of history, better in his turn of phrase, and best of all in his delightful vignettes." - Independent on CATHOLICS

"Richly entertaining... Excellent." - Literary Review on CATHOLICS