John Cameron was born on January 22, 1843, in Markham, Ontario.

He was a newspaperman and officeholder. He was educated in Markham and then in London, Ontario. In 1859, he began an apprenticeship as a printer with the London Free Press and during the next four years, he learned his trade in London and Sarnia. In 1863, he returned to London and purchased the press from Joseph Hiram Robinson in return for a commitment to continue publishing his Evangelical Witness, organ of the Canadian Wesleyan Methodist New Connexion Church. He also immediately began planning his own newspaper and on October 27, 1863, he started the daily London Evening Advertiser and Family Newspaper, politically independent and produced in a small format. Involving his family in the business (his brother William as local editor and manager, and his father, William Sr, as a bookkeeper), it was an instant success and within a year it was enlarged to full broadsheet size. The Weekly Advertiser was added in 1864, and a morning edition was started in 1878. The newspaper’s growth brought Cameron financial independence and status in the community and in the industry. He joined the Canadian Press Association, serving as its president in 1872 and 1875. Cameron’s family had long supported the Reformers and he also held advanced Liberal views, so it was perhaps inevitable that the Advertiser became a Liberal standard-bearer. By the early 1870s, it was the second most important Liberal publication in Ontario after the Toronto Globe, published by George Brown. In January 1875, Cameron moved to Toronto to begin the Liberal, a morning daily. Competition from the Globe was fierce and the cost of publishing in Toronto greatly exceeded his expectations. As a result, the Liberal suffered heavy losses and in June he closed the newspaper and returned to London. In 1882, after the political victory of his supporter Edward Blake, Cameron was named managing editor of the Globe. In 1890, he stepped down and returned to his Advertiser. Facing increased competition and financial problems, Cameron was forced to sell it to Thomas Hunter Purdom, a London lawyer and a Liberal. In 1903, he was appointed as postmaster of London, a position he held until his death from a heart attack in 1908.

In 1869, he married Elizabeth Bessie Millar (1851-). He died on December 1, 1908, in London, Ontario.