This essay highlights a recent re-discovery at The British Library: an extra-illustrated copy of George Walter Thornbury's The Life of J. M.W. Turner, London, 1862 (Tab.438.a.1). Thornbury is still a standard source for the history of this great British artist, but this unique copy enhanced with over 1,600 portraits, views, engravings, drawings and letters collected by John Platt (1842-1902), a retired businessman from Warrington, has had little exposure. Platt's additions bring Thornbury's story to life, and include drawings, watercolours and manuscripts by some of the most significant figures in the history of British art, including Turner, Paul Sandby (1731-1809), John Robert Cozens (1752-1797), Francis Nicholson (1753-1844), Joseph Farington (1747-1821) and John Constable (1776-1837). The essay explores the practice of extra-illustration in the late nineteenth century, the contents of this collection, and what can be traced about its compiler, John Platt.