John Howell became a naval apprentice at the age of fourteen, later joining the Merchant Navy. He arrived in Sydney in 1854 on the Flash and for two years traded on merchant vessels on the east coast of Australia and between London and Port Adelaide. His seafaring career was not without adventure, as he was 'cast away' and rescued on two occasions.
In 1856 he entered Government service in Australia as a convict guard, being promoted a year later to the position of Chief Guard. He later worked as a mail guard for the Post Office on the run between Adelaide and Port McDonnell, and then as Keeper of the Port Augusta Gaol, before being promoted to Governor of the Adelaide Gaol in 1873. He was appointed Justice of the Peace in 1882.
Howell was known as an ardent admirer of Burns and Robert Herrick, and he himself published verse and was admired by his contemporaries for his sympathy with nature. He was a contributor to the Adelaide Miscellany.
His son, Frederick John Howell (qv), published a book of verse.