When Danielle Allen unearthed a parchment of the Declaration of Independence buried away in Sussex, England, little did she know that she had discovered a story of historical magnitude that would alter our understanding of British and American history. Revealing that the Age of Revolution began earlier than we thought—not with the Boston patriots nor with the Parisian Jacobins, but in Britain itself—Allen demonstrates in Radical Duke that the rights of man, the theory of revolution, and calls for popular sovereignty all emerged from the radical energies of London before they spread across the Atlantic and the Channel. At the center of this new age was Charles Lennox, the progressive Third Duke of Richmond, a rarely cited historical figure who becomes the biographical focus of Allen’s groundbreaking work. Even with royal blood coursing through his veins, the handsome, gallivanting Duke (1735–1806) preferred to rub shoulders with ordinary folk—supporting the rights of jurors, freedom of the press, and religious toleration. As Allen shows, from 1767 to 1782, he was England’s leading voice of opposition to the Crown, and, as the leader of the Sussex militia, even a threat to the King’s power. But the Duke did not challenge the Crownalone. The archives have long hidden the covert alliance between the young Duke and his age-mate Thomas Paine, the future author of Common Sense. While working as an obscure tax collector, Paine was engaged by the Duke to contribute to the most influential but anonymous newspaper essays of the age, The Letters of Junius, which spawned sedition trials, defined the rights of man, and brought England to the brink of revolution. Along with a small cadre of radicals, Paine and the Duke fired hearts across two continents and secretly stoked a burgeoning political movement. Throughout Radical Duke, Allen sets the record straight. Through archival evidence, confirmed with computational tools, she reveals the anonymous authors of the inflammatory Junius letters; she also identifies a new Paine work, his first book, The Juryman’s Touchstone, cowritten in 1771. In the end, the Duke swerved. He did not advocate the overthrow of the monarchy but remained loyal to both Crown and people, launching an age of reform. With her penetrating prose, Allen resuscitates a seminal political figure who has been egregiously neglected throughout history.