 McCaul served until 1853, when he became the head of University College, a constituent college of the University of Toronto.During the Trent Affair of 1862, William Mulock asked John McCaul as the head of the college to call a student meeting that led to the formation of the University Company of volunteers, later K Company of the Queen's Own Rifles.McCaul was also a dedicated musician and was president of the Toronto Philharmonic Society from 1845 to 1847.