Born in Southall, London on 3 November 1840, Leary emigrated in 1854 to Victoria, where he worked in the timber trade and in the goldfields.

In 1861, he left for Dunedin, and spent time in the diggings at Gabriel's Gully, before returning to Dunedin where he became a partner in an auctioneering and accountancy firm, Leary and Grant.

[1] In 1862, Leary married Carolina Georgina Pope of Ballarat, Victoria.

[2] During his time as Mayor of Dunedin, Leary investigated the bookkeeping of the gas department, which led to the sacking of the manager, although he was later reinstated.

In 1894 Leary traveled to London to sort of Dunedin loan's,[clarification needed] but while there caught pneumonia and died, on 14 May 1895, leaving a widow and one son.