J J Simington joined the staff of The Irish Times in 1878, less than two decades after the newspaper had been founded, quickly becoming chief clerk and subsequently being appointed general manager, a position he held for 34 years. As he advanced in years he became the venerable elder statesman of the Dublin newspaper world, retiring as manager in 1941. However, already a member of the board, he continued with the company as a director until his death, aged 87, in 1949, thus establishing a record length of service with The Irish Times unlikely to be matched.

In appearance he was tall and very thin, sporting a goatee beard, and even in his eighties he could ascend and descend the wide staircase leading to the boardroom two at a time. During the Civil War he refused an offer of special protection either at his office or at his home. Staff at the time remembered that he had an almost school-boyish interest in everything, including a collection of autographs, postage stamps and old Dublin directories, and it was also recalled that he had a habit of writing reminder notes to himself, filing them in an enormous roll-top desk.

During 1939, to mark Simington's 60 years with the paper, the company arranged a special presentation at which he was described as "an astonishingly youthful figure… a miracle of septuagenerian youth, at his desk from early morning until late… thinking of twenty things at once and generally doing half a dozen of them, bubbling over with energy and enthusiasm." The directors and over two hundred staff members contributed to his presentation, a portrait of himself painted by the well-known artist, William Conor, who had already painted portraits of Douglas Hyde and the newspaper's editor, R. M. Smyllie.

Louis O'Neill's finest hour as general manager and later group chief executive of the Irish Times was the purchase of a Uniman colour press which provided colour advertising and allowed for extra sections with the newspaper.

In 1984, the Irish Times along with other newspapers had a windfall when the Reuters newsagency in which they held shares was floated on the London Stock exchange. In The Irish Times' case the sum amounted to £3 million. Although the new press was comparatively small, and operated on a very cramped site in D'Olier Street, it formed the basis of a 15-year period of growth in pagination, circulation and turnover when it was commissioned in 1986, as property, business and weekend supplements extended the reach and appeal to readers and advertisers alike.

A typical Monday newspaper pre-1986 was made up of 18 or 20 pages.

When a sports supplement was added post 1986, this went up by at least eight pages. The Irish Times circulation rose from 1985's 86,000 to 116,280 in 2000, the year after he retired.

Every year, Louis O'Neill presented the financial results to the staff in video form, known familiarly as "Louis –the Movie" followed by a question and answer session in which he always emphasised the need for putting something by – newspaper publishing is cyclical, he always insisted. When he stood down after 22 years of management, he received an unusual honour, a presentation from the National Union of Journalists' chapel (office branch), a recognition of his contribution to the well being of the business and those who worked for it.