Grant went to India in 1767 in the service of the East India Company and, following the deaths of two young daughters, became a committed Christian. He rose to great wealth and prominence, ultimately became chairman of the board of directors of the East India Company, and at his residence in Clapham was an active member of the Clapham Sect. Among other achievements, he supported the building of churches in India and elsewhere, procured the assignment of a grant for education and introduced Sunday schools into Scotland.