Dennis Sewell - Turncoat: Roundhead to Royalist

Who was George Downing? He was one of the English Civil War's most cunning spies and head of Oliver Cromwell's military intelligence, before spectacularly defecting to the Royalist camp.

He had a hand in founding New York, and built the street where our Prime Minister lives.

But he has remained an elusive figure in history, as if hiding himself in the footnotes.

Historian Dennis Sewell tells the full story of Downing's life for the first time, following the elusive man from Puritan New England, through battlefields, courts, and parliaments, to the heart of Restoration London.Talking to Tiffany Murray