Born at Trewarthenick near Tregony, an estate near Tregony with two and a half miles of river frontage on the River Fal, he was also the younger brother of Francis Gregor (1760 – 1815) who was Member of Parliament for the county of Cornwall between 1790 and 1806.

Educated at Bristol Grammar School, where he became interested in chemistry, and then Cambridge (St John’s College) he was ordained in 1787 and was appointed curate at St Mary’s Church in  Diptford, near Totnes.  In 1790, after a brief period at Bratton Clovelly, he was appointed to the living of Creed.

Being a wealthy man, he was able to indulge in his interests in chemistry and geology and he began a systematic chemical analysis of Cornish minerals.  In 1791, he collected samples of a mineral now named ilmenite from the Manaccan Valley and isolated the oxide, then described as a calx, of a previously unknown metal from which he named the ore, ‘Manaccanite’.  Some months later, the discovery was repeated by a German geologist, Martin Heinrich Klaproth, who named the metal  titanium, which name has been kept. 

Gregor was a founding member of the Royal Geological Society of Cornwall (February 11th) and was also a respected landscape painter, etcher and musician. He died of tuberculosis in 1817 at the young age of fifty six.