 In 1875, he moved to London, joined the Architectural Association and began work as an assistant to Richard Coad - who recommended MacLaren to the Royal Academy Schools in January 1876.During 1878, he was in the office of the Surveyor of Public Buildings for the County of Surrey.During the early 1880s, he lived at 40 Montpelier Square, London, with his brother Thomas, also an architect.