Born in Portsmouth in 1752, Thomas Oakes was one of two sons of Matthew and Mary. In 1770, he sailed to Madras, India and joined the East India Company. He served the Company for forty-six years and retired in 1816. In 1786 he married Elizabeth Ann Cosby, with whom he had three sons and three daughters. Elizabeth died in the late 1790s and in 1803, Oakes married Maria Lucy Gahagan, daughter of Physician General of the East India Company.