 While stationed at St. James's Parish, and with the blessing of the parish priest, Henry Cunningham, O'Brien expanded the choir and had the organ refurbished.Masses by Palestrina and Mozart were sung in their liturgical settings, and these were extended to public performances with the choristers now firmly established as the St. James's Choir.Their first major event was an RTÉ TV showing of Gounod's "St. Cecilia Mass" on her name day, 22 November 1971.