He was born in Inverell to schoolteacher William John Cahill and Ada, née Radford.
He attended De La Salle College in Armidale and the University of Sydney, where he studied pharmacy.
From 1926 he ran a pharmacy in Tamworth which he expanded to a chain across northern New South Wales.
He was expelled from the ALP in 1959 for voting against the abolition of the Legislative Council, whereafter he was a member of the Independent Labor Group.
This article about an Australian Labor Party member of the Parliament of New South Wales is a stub.