John emigrated to Canada in 1834 and settled in Montreal where he became a prominent architect, the Provincial Surveyor and a Justice of the Peace. He served his apprenticeship with the Surveyor Andre Trudeau. His wife came from a family linked to the local construction industry.
John pursued his career as surveyor until 1852. During this time he also worked on various designs for architectural projects. His first assignment was the Customs building in Montreal. He then produced a design for the arts faculty and training college of McGill University, along with plans for the Montreal Law Courts. His first important undertaking in the field of ecclesiastical architecture was the construction of the towers for Notre-Dame Basilica in Montreal. He then undertook to draw up plans for several churches including the churches of Sainte-Anne and Notre-Dame-de-Grace in Montreal and was the architect for the Episcopal palace there. He also designed the Redpath Sugar Refinery. Ostell Crescent in Montreal is named after John.