Montfort Secondary School first began in a humble way. Sometime after the outbreak of World War I, Father Laurent, Parish Priest of Serangoon, laid between the parish church and his presbytery the foundation of a two-storeyed building for a school. His successor, Father H Duvelle, started a Chinese class began on the ground floor of the newly completed building and an English class on the top floor, engaging Mr Lee Ah Kow to run the classes.
From 1922 to 1936, Mr PA D’Costa was recruited to be Principal of Holy Innocents English School and the school grew from strength to strength. In 1936, Mgr A Devals, the Bishop of Singapore and Malaya invited the Brothers of St Gabriel to run the Parish School. Brother Gerard Majella, Brother John de Breboueuf, Brother Francis Tessier and Brother Louis Gonzaga were some of the first Brothers to arrive in Singapore to start up the Gabrielite approach to education.