He was born at the Trewarthenick Estate in Cornwall, the son of Francis Gregor and Mary Copley and the brother of Francis Gregor, MP for Cornwall. He was educated at Bristol Grammar School, where he became interested in chemistry, then after two years with a private tutor entered St Johns College, Cambridge, graduating BA in 1784 and MA in 1787. He was ordained in the Church of England. He became vicar of St Marys Church Diptford near Totnes, Devon. He married Charlotte Anne Gwatkin in 1790 and they had one daughter.