These biographical notes have been mainly extracted from "Australian Dictionary of Biography, Volume 10", published in book-form in 1986 and online in 2006. It was written by James Griffin. The war-service information was sourced from Wikipedia.

Michael James (Mick) Leahy (1901-1979), explorer, was born on 26 February 1901 at Toowoomba, Queensland, fourth of nine children of Irish migrants Daniel Leahy, railway guard, and his wife Ellen, née Stone. He was educated at Christian Brothers' College, Toowoomba. He eventually became leader of the most enterprising expatriate 'clan' on the New Guinea frontier, where, from the 1930s, a million people were brought under Australian control.

In 1930 Mick Leahy and Michael Dwyer were staked to prospect the Ramu River tributaries. Tracing the Dunantina River they glimpsed the Goroka valley, then unexpectedly were led south to the junction with the unknown Wahgi River.

In November 1930 Leahy and Dwyer were the first Europeans into the Gafuku (Asaro) valley. Mick accepted a stake from New Guinea Goldfields Ltd (N.G.G.L.) in 1931 and, after aerial reconnaissance, a decisive factor in Highlands exploration and then almost unique to New Guinea, led an expedition into the Watut valley.

Leahy took correspondence lessons in photography and journalism and carefully kept a diary. His meticulously organized expeditions in 1933 brought himself, his brother Danny, and Charles Marshall of N.G.G.L. to a Pisgah view of the populous Wahgi valley from Mount Erimbari on 15 February. In April, with J. L. Taylor, representing an administration urged by the League of Nations to fill in cartographical blanks, the Leahys crossed Chimbu territory to Mount Hagen, tracked the Baiyer River towards the Sepik and, via the lower Jimi River, returned to climb Mount Hagen and explore south to the Wahgi-Nebilyer divide.

On 5 March 1940 Leahy married at St John's Church, Darlinghurst, Sydney, a 19-year-old North Queenslander Jeannette Gwendolin Best. They had five children who went into professions and business but Mick could not acknowledge three mixed-race sons at Mount Hagen who came under Danny Leahy's patronage and thrived.

During the Second World War he joined the Royal Australian Air Force as a flight lieutenant and was assigned to the US chief engineer to build an airstrip in Telefomin. For his services during the war Leahy was awarded the US Medal of Freedom with bronze palm in 1948, appointed a Member of the Order of the British Empire (MBE) in 1952 and made an honorary member of the Explorers Club in 1959.

Survived by his wife, he died on 7 March 1979 and was buried at Zenag (on the Lae to Bulolo road) with Catholic rites.