[3] The clergyman was appointed by Dorchester as garrison chaplain of Montreal in 1766, with inaugural service in Christ Church was pronounced by him on 20 December 1789.

Before construction began, Willis died, and Montreal architect Thomas Seaton Scott (1826–1895) was commissioned to carry out his design.

This defect formed the basis of an important lawsuit concerning builder's liability, which went all the way to the Judicial Committee of the Privy Council, at that time the highest court in the British Empire.

New foundations were poured in 1939, and in 1940, an anonymous donation permitted the construction of a much lighter steeple made of aluminum, molded to simulate the former stone spire.

The earlier instrument was constructed by William Hill and Son in London to duplicate an organ given to the congregation by King George III and destroyed in the fire of 1856.

This project allowed for the linkage of the eastern and western branches of Montreal's underground city, connecting the Eaton's store (subsequently Complexe Les Ailes) and The Bay's Henry Morgan Building.

The guards maintain their traditional ties with the church, as well as to McGill University, by marching from the Arts Building on campus, to the cathedral, annually in commemoration of Remembrance Day.

Every Saturday at 2pm throughout the year the cathedral hosts a series of free weekly concerts, "L'Oasis musicale," which supports and promotes young aspiring musicians, many of whom are studying at music colleges in Montreal and starting out on their careers.

The concerts feature a range of musicians, from solo instrumentalists and singers to ensembles, small orchestras, and choirs.