Henry Yates Thompson was one of the late 19th and early 20th century's great bibliophiles and collectors of medieval manuscripts. His passion was directed by an inheritance of ten medieval manuscripts from his maternal grandmother and throughout his long life, he steadily increased and constantly refined his collection. His largest and most spectacular purchase was a group of more than 200 manuscripts from the Earl of Ashburnham in 1897 known as the 'Ashburnham Appendix'. His collection was eventually sold in three sales at Sotheby's in 1919, 1920 and 1921 (it was around this time that Sotheby's began to auction items other than Books, which it had done almost exclusively since its foundation).
Yates Thompson was head boy of Harrow School and won the Porson prize for Greek verse at Trinity College, Cambridge. Besides his collecting of manuscripts, he was the proprietor of the Pall Mall Gazette which his father-in-law made over to him in 1880. Newspaper ownership evidently gave him little reward and in 1892 he sold, not unprofitably, to William Waldorf Astor. He married in 1878, Elizabeth, daughter of George Smith, founder of the Dictionary of National Biography. They lived at 19 Portman Square and Oving, Buckinghamshire. A group of forty-six illuminated manuscripts was left by his wife to the British Museum, known as the Yates Thompson collection (A. Bell, 'Thompson, Henry Yates (1838-1928), Oxford Dictionary of National Biography, Oxford, 2004).