When he became the owner and editor of The Hibernia, he changed its ethos to be more left-wing and republican and moved it to a fortnightly schedule.
[3][4] Following the closure of The Hibernia in 1980 due to a lawsuit, he co-founded The Sunday Tribune.
After the turmoil in the Tribune, from which he exited early, in 1983 he founded the political, current affairs and business magazine, The Phoenix.
Another effort at launching a magazine in the early 1980s was Digger, his father's nickname since he was involved in the mining industry in Australia.
His son Aengus worked for The Phoenix, his daughter Brigid is also a journalist, and his son Michael Mulcahy was a Councillor, TD and former Lord Mayor of Dublin.