[2] In 1952, he commenced a six-year apprenticeship as a hand and machine compositor with Truth and Sportsman, publisher of the Sydney Daily Mirror.

After completing his apprenticeship and military draft commitment in the Australian Army, he traveled to the United States, where in 1958, he joined the International Typographical Union in San Francisco.

Disenchanted with union politics,[4] he joined a research and development team within Murdoch's News Limited and after a short time was selected to lead the company's industrial relations.

O'Neill and fellow British negotiator, John Collier, were named Joint General Managers of Times Newspapers Limited and appointed to its board.

[9] His responsibilities involved the New York Post, the Boston Herald, the San Antonio Express-News and the Chicago Sun-Times.

[11] Most of 1986 saw him fulfilling the role of General Manager at the New York Post[12] and meeting with the British unions in an attempt to bring the strike to an end.

[17] On 25 November 1990, O'Neill arrived in Geneva, Switzerland to represent the United States as the employer delegate at a tripartite meeting[18] of the International Labour Organization.

[25] Following his retirement O'Neill compiled a memoir that dealt with his involvement in the acquisition of Times Newspapers, the Wapping Strike and the reacquisition of the New York Post.