By the middle of the 19th Century the development of the city and the consequent increase in the Catholic population of Rathmines necessitated enlargement of the church. 

In July 1848, a visiting missionary priest, Fr. Gentili of the Order of Charity, described some beautiful churches he had observed in Italy and called for the building of a new church in Rathmines. In September of that year, a public meeting was held to discuss the proposition to build a bigger church. Fr Stafford immediately donated £1,000 towards the construction costs.