His father, a blacksmith by profession, was one of the founders of the Australian Labor Party (Tasmanian Branch) and represented Tasmania in the Senate from 1914 to 1920.

He was the state secretary of the Australasian Meat Industries Employees' Union from 1911 to 1916 and served on the Butchers' Wages Board.

[2] Guy was elected to the Division of Bass in the Tasmanian House of Assembly in 1916 and was part of Joseph Lyons' cabinet when Labor came to power in 1923.

Lyons was severely injured in a car accident in July 1926, and Guy was acting premier for four months in his absence.

One of Guy's responsibilities was to defend film-censorship provisions which he described as 'both necessary and admirable', for, without them, 'all sorts of puerile and undesirable films could be displayed, to the detriment, not only of our civilization, but of the Christian religion'.