Mgr.Gandy was the coadjutor of Mgr.Laouenan since 1883. He succeeded automatically Mgr.Laouenan when he died. He knew the diocese more than any other bishop. He used to visit every village of every parish. In the absence of Mgr.Laonenan while he was in Europe, between 1884 to 1886, he managed the diocese very well. In 1889 he was given the title of Archbishop of Claudionopolis. In 1892 he became officially the Archbishop of Pondicherry.
Pondicherry, now an Archdiocese, had Mysore, Coimbatore and also Malaca – Singapore as its suffragan dioceses.
Thanks to the influence of the devotion to Sacred Heart of Jesus at Montmartre in Paris, Mgr.Gandy consecrated the Archdiocese of Pondicherry to the Sacred Heart of Jesus in June 1895. He planned to have a new large Church of Sacred Heart constructed in Pondicherry. On the 27th January 1908 Mgr.Gandy celebrated solemn mass in the new sacred heart church built by Fr.Telesphore Welter MEP.
