He primarily inherited debt when his father died when he was ten, but through family connections had a successful career with the East India Company.

His mother educated him herself until through the influence of Charles Bunbury, John entered the service of the East India Company (EIC) in 1769 as a "writer", i.e. a junior clerical worker.

[1] However John progressed, becoming a Persian translator in 1775 for the EIC Army, a mercantile factor in 1776, Sheriff of Kolkata for 1779.

His wife died on 6 September 1803, and John returned to India filling the post of collector of customs, at Kolkata.

[1] He died in 1818 and was buried in the South Park Street Cemetery in Calcutta (today Kolkata), India.