Lemon was born in Montreal around 1815 and entered the service of the Hudson’s Bay Company in 1833. He served as a middleman at Fort McLoughlin in 1842 before being transferred to Fort Victoria in 1843 where he took part in building the new fort. Lemon's duties at the fort were varied but tended to include mainly carpentry and gardening tasks. He had two wives throughout his stint at Fort Victoria. There is no record of his first marriage in the Journal; only that, on February 28, 1847, "John Lemon's wife departed this life about 3 P.M. after a long illness". His second marriage took place on July 9, 1848 when he was among a group of five men married by Mons. Veyret to unnamed women. Father Lempfrit credited Lemon ("Jean Leman") with delivering the manuscript for his 1848 Oregon Trail Journal to the Grey Sisters in Montreal in 1850. Following retirement from the Hudson's Bay Company Lemon was briefly a member of the Victoria Voltigeurs; Victoria's first police force. In 1861 and 1863 he pre-empted land in Cowichan where he settled with a daughter and operated the Cowichan Hotel. In June of 1864, Lemon accommodated Robert Brown and the Vancouver Island Exploring Expedition. He died following a skull fracture sustained in a fall in 1883.