In 1893, Hill joined the British Museum in the Coins and Medals Department. At that time, the Department was the center of study of Greek coins. Hill continued the work of Barclay Head and Reginald Poole; in 1897 published the first volume of a catalogue of Greek coins. Hill subsequently produced catalogs on many of the British Museum's collections in his area. In 1912, he became Keeper of the Department. In 1931, he was appointed Director and Principal Librarian of the British Museum. Whilst director, he purchase the Codex Sinaiticus from the Soviet Union and, with the Victoria and Albert Museum, the George Eumorfopoulus oriental antiquities collection.