Ailsa was the only daughter of Pittsburgh banker and National Gallery Founder Andrew W. Mellon [1855-1937] and his wife Nora McMullen Mellon [d. 1973], who divorced in 1912. The son of Irish immigrant Thomas Mellon [1813-1908] and his wife Sarah Jane Negley [1817-1909], Andrew W. Mellon was born in Pittsburgh. Thomas Mellon came to America in 1818 with his parents, and through his entrepreneurial skills and fortuitous investments became a very wealthy and powerful man with a career as a lawyer and later a judge, and a banker. Two of his four sons, first Andrew and then Richard B. [1858-1933], succeeded him as head of the Mellon family bank, established in 1870.In 1920 Andrew left Pittsburgh to serve as Secretary of the Treasury in Washington, a post he kept until 1932. He was Ambassador to Great Britain from 1932 until March 1933, after which he moved back to his native city. The remainder of his life was devoted to philanthropy.
Andrew W. Mellon was a keen collector of art. He bought his first painting around 1880 during a trip to Europe with Henry Clay Frick.Inspired by London's National Gallery, Mellon had the idea of turning his collection into the foundation of a National Gallery of Art in Washington. In 1930 he established the A.W. Mellon Educational and Charitable Trust, the medium through which he made his gift to the nation. Mellon returned to Washington in 1937 for the purpose of overseeing the construction of the National Gallery, but he died before its opening in 1941.
Ailsa attended boarding school and later Miss Porter's School for Girls in Farmington, Connecticut. As a teenager she spent her summers in Europe. When Ailsa was twenty years of age, she moved with her father to Washington, where Ailsa acted as his official hostess. She had a full social life, and almost became engaged to Prince Otto von Bismarck, grandson of the Iron Chancellor. Instead in 1926 she married David K. E. Bruce [1898-1977]. As a wedding gift, Andrew Mellon purchased for his daughter the "Woodlands" estate at Woodbury, Long Island, since been purchased by the town of Oyster Bay. Member of an old Southern family, David Bruce worked as Vice Counsel for the State Department, and later as Ambassador to the Court of Saint James in London. The Bruces, who divorced in 1945, had one child, Audrey, born in 1934. Audrey married Stephen Currier, with whom she had three children, Andrea, Lavinia, and Michael. Audrey and Stephen were presumed dead in 1967 when a plane in which they were flying in the Caribbean disappeared. At her death in 1969, Mrs. Bruce bequeathed 153 paintings, primarily by French artists, to the National Gallery, as well as establishing a fund for future acquisitions.