became senior partner in 1880. He was also a director of two publishing houses, Oliver and Boyd and Gurney & Jackson. During his tenure, the firm concentrated on academic and theological books, and on antiquarian and second-hand volumes. The shop further expanded into various rooms and flats in the South Bridge building. James Ainslie Thin (1882–1972). James Hay Thin's eldest son. He joined the firm shortly before World War 1, spent two years in a German POW camp, returned to the business after the war and remained until the 1950s. Thomas Thin. James Hay Thin's younger son who also worked in the business. James Thin (1923–1997), known as Jimmy Thin. J. Ainslie Thin's son. He worked in the firm from 1949 to 1990, during which time he built up the mail order side of the business. David Thin (born 1933), known as Ainslie Thin. He joined the firm in 1957 and went on to become chairman and managing director, overseeing a period of considerable expansion. Jackie Thin. Ainslie Thin's eldest daughter. A qualified chartered accountant, she served as finance director and then managing director. Hilary Thin. Another of Ainslie Thin's daughters. She was in charge of the chain's Scottish region. Jamie Thin. Ainslie Thin's son. With an MSc in computing, he ran the firm's computer systems. When Jimmy Thin joined the firm in 1949, the business occupied sprawling premises on several floors of the South Bridge / Infirmary Street block. Over the next few years, these separate units were consolidated into a single shop, using 55 South Bridge as its main address. This was to remain the flagship shop and head office for the rest of the firm's existence. During the second half of the 20th century, the business underwent rapid expansion. It opened new shops and bought existing shops throughout Scotland and England. By 1990, it had grown to a chain of 34 stores, stretching from Inverness to Portsmouth, with an annual turnover of £34 million. In 1994, it purchased the Volume One chain in England for £4 million. The firm also had interests in publishing. Between 1900 and 1962, it was joint owner (with James Grant, Booksellers) of Oliver and Boyd, a large Edinburgh-based publisher of school books, theological books and literary works. Thin's share of that business was sold in 1962 to pay death duties. In 1970, Jimmy and Ainslie Thin established the Mercat Press imprint, specialising