He was a Liberal Party of Australia member of the Western Australian Legislative Council from 1948 until his death, representing Metropolitan Province.
[1] Hearn was born at High Wycombe in Buckinghamshire, England, where he entered the furniture-making trade.
He migrated to Western Australia in 1912, and along with his brother Ernest, formed Hearn Bros and Stead Pty Ltd, based out of a converted church in Victoria Park, with each serving as joint managing directors.
[1][11][12] He had a number of parliamentary assignments, including as a member of the Joint House Committee from 1950 to 1956, a member of the Select Committee on the Provisions of the Kauri Timber Co Ltd Agreement Bill in 1950, chairman of the Honorary Royal Commission inquiring into the Town Planning and Development Act Amendment Bill from 1951 to 1952 and chairman of the Select Committee on the Workers' Compensation Act Amendment Bill in 1954.
[14] As a result of the visit Hearn paid for the Crown Jewellers to make the black rod as a gift to the Legislative Council that is used today.