From Westminster he was elected to a studentship at Christ Church, and in due course he took holy orders, and became the Rector of Semly in Wiltshire. It was not long, however, before he was back again in Oxford, for George I. upon his foundation in 1723 of the professorship of Modern History (with which at that time the modern languages were associated) appointed David Gregory to the chair. He was thus the first Professor of Modern History at Oxford. Of his work as a lecturer there is no record, but that he was thorough and painstaking no one can doubt; for realising that the amount of work was too large for one man to accomplish, he introduced several foreigners as teachers of their own language, and until such time as they were self-supporting he provided for them out of his own salary. Fortunately his chair was a lucrative one. He took the degree of B.D. on March 13, 1731, and that of D.D. on the 7th of July of the following year, and four years later he was appointed Canon of Christ Church. On undertaking this office he resigned his professorship. While he was canon, it was one of his most congenial tasks to superintend the restoration of the Great Hall, and before it was completed, he presented busts of his early patron George I. and of George II., who was then on the throne. The new library was also finished under his care, and the interior, with its graceful pillars, its delicately moulded roof and wide windows, was executed entirely according to his taste, and under his personal supervision. Little did he think as he guided the placing of the volumes, how one day his own beautiful collection of books would take its place there out of the reach of his son’s creditors. If Dean Gregory had been alive in 1775, the old library, which had been the monastic refectory, would never have been mutilated, as it was, for the accommodation of the Westminster students.