The early part of William Boag's career was spent in Sydney where he was in partnership with portrait photographer Joseph Charles Milligan. (Images made by Boag are in the collection of the Campbelltown and Airds Historical Society.). Boag arrived in Queensland in November 1871. He travelled around the south-east, along the foreshore of Moreton Bay and the township of Cleveland. He then moved into the Logan and Albert area where he captured images of local crushing mills and sugar plantations. While at Yatala, he took on a partner, John Henry Mills, and by the end of 1872, both men were in Stanthorpe where they remained for several months, producing views of the booming tin-mining settlement. In July 1873, after stopping off in Warwick, Boag and Mills extended their operations to Mackay, where they remained until October 1875. During this time, Boag made trips to St Lawrence and Cooktown, however his movements after this are difficult to trace. It is known that by mid 1876 he was at Copperfield and Clermont, and in February 1878, he inserted a notice in the Peak Downs Telegram announcing that he was leaving for the west. Then information ceases abruptly. It is possible that Boag never reached his destination, since his death certificate records that he died in 1878 at an unknown location.