Paul Mellon (1907–99) was the only son of Pittsburgh financier and industrialist, Andrew W. Mellon, and his English wife, Nora McMullen. Baptized in St. George's Chapel, Windsor, he spent his childhood summers in the English countryside, where his lifelong love of British culture began.

After attending the Choate School in Wallingford , Connecticut (1919–25), he studied at Yale (1925–29) and then pursued his interest in English literature at Clare College , University of Cambridge ( England ), for two years (1929–31). There he enjoyed rowing on the Cam and developed a passion for horses, most especially riding and foxhunting. The latter, in turn, led him to collect books on hunting and racing. In later years he would become a breeder of horses and was a champion trail rider well into his seventies. He took special pride in the fact that his horse Mill Reef—considered one of the greatest horses of the twentieth century—won the English Derby and l'Arc de Triomphe in 1971.

Paul Mellon stayed in England while his father served as the U.S. Ambassador to the Court of St. James (1932–33) after having served as Secretary of the Treasury (1921–32) under three Presidents. On his return to Pittsburgh , he worked briefly as a clerk at the Mellon Bank but elected not to pursue a career in business or banking. Instead, he chose to move to Virginia with his first wife, Mary Conover Brown, whom he had married in 1935 and with whom he had two children, Timothy and Catherine. In 1941 he enlisted in the Army and asked to join the cavalry. After two years in Fort Riley , Kansas , he served in the Office of Strategic Services in England and rose to the rank of major.

Tragically, Mary died from an asthma attack in 1946. Two years later Paul Mellon married Rachel (Bunny) Lambert Lloyd, an avid horticulturalist and gardener, whose fondness for French Impressionist and Post-Impressionist painting, as well as American art, he came to share.

In 1936 Paul Mellon had purchased his first British painting, Pumpkin with a Stable-lad by eighteenth-century British artist George Stubbs, who remained a favorite of Paul Mellon's throughout his life. With the help and encouragement of English art historian Basil Taylor, starting in the late 1950s, he acquired many works by British artists and, by the mid-1960s, amassed a major collection that included works by both under-appreciated artists (such as Stubbs, Arthur Devis, and Joseph Wright of Derby) and those who were well known (for instance, William Hogarth, J. M. W. Turner, and John Constable). London art dealer Geoffrey Agnew once said of his acquisitions: “It took an American collector to make the English look again at their own paintings.”

While Paul Mellon did not share his father's interest in business, the two found common ground in their love of art and philanthropy. Shortly before Andrew Mellon's death in 1937, construction began on the West Wing of the National Gallery for which the senior Mellon had provided funds. Four years later Paul Mellon presented both the building by John Russell Pope and his father's collection of 115 paintings to the nation. He served on the museum's board for more than four decades: as trustee, as president (twice), as board chair, and as honorary trustee. Paul Mellon commissioned I. M. Pei to build the East Wing and, with his sister Ailsa, provided funds for its construction in the late 1970s. Over the years he and his wife Bunny donated more than 1,000 works to the National Gallery, among them many French and American masterworks. His generosity extended to other museums, including the Virginia Museum of Fine Arts and the Yale University Art Gallery .

Paul Mellon's largesse to Yale University knew no bounds. To date, he is one of the University's most generous benefactors. In 1966 he gave the building, works of art, and endowment that established the Yale Center for British Art, and was also responsible for the creation of its sister institution in London, the Paul Mellon Centre for Studies in British Art, which supports teaching, scholarship, and publication. In addition, he endowed two residential colleges (Stiles and Morse) as well as the masterships and deanships of all twelve of Yale's residential colleges, numerous professorships and fellowships, and interdisciplinary programs in the humanities, and he supported teaching in the Schools of Medicine, Divinity, and Forestry & Environmental Studies. While he claimed no credit and insisted that the Yale Center for British Art not carry his name, Paul Mellon wished to privilege others as he had been privileged.

Paul Mellon was a private man, modest and mild-mannered. He was a wonderful conversationalist with a quick wit and a self-deprecating sense of humor. As an exemplary donor, he quietly supported the causes in which he believed: higher education, the arts and humanities, poetry, religion and psychiatry, and conservation and the environment. He will be remembered as a collector and connoisseur, patron and benefactor without equal, and he will live on in countless institutions and organizations that continue to benefit from his extraordinary generosity.

Near the end of his autobiography, Reflections in a Silver Spoon (written with John Baskett and published by William Morrow and Company, New York, 1992), Paul Mellon wrote: “I have been an amateur in every phase of my life; an amateur poet, an amateur scholar, an amateur horseman, an amateur farmer, an amateur soldier, an amateur connoisseur of art, an amateur publisher, and an amateur museum executive. The root of the word “amateur” is the Latin word for love, and I can honestly say that I've thoroughly enjoyed all the roles I have played.”