After working as a postdoc at the University of Manitoba, Bancroft returned to Cambridge as a Fellow at Christ's College.
Bancroft returned to Canada in 1970, as an assistant professor in the department of chemistry at the University of Western Ontario (UWO), becoming a professor in 1974, spending two periods as head of department. Bancroft was director of the Centre for Chemical Physics from 1977 to 1981, establishing Surface Science Western during his tenure. At UWO Bancroft became interested in photoemission spectroscopy, and in 1972, with National Research Council (NRC) support, a spectrometer was purchased for research using far ultraviolet and X-ray photons. This purchase also involved the universities of Toronto and Windsor in a Southwestern Ontario consortium.