A civil servant, lecturer and researcher, he worked with Fianna Fáil Taoiseach Charles Haughey to formulate his economic strategy The Way Forward and directed his and subsequent administrations from the 1980s until Kennedy's retirement.
In 1958, he won a competition to become an elite officer in the Department of Finance, but then had tuberculosis; whilst recovering, he read for a master's in economic sciences from UCD and graduated with first-class honours and a travelling scholarship for his dissertation in 1960.
The Department's Secretary, and founder of the ESRI, T. K. Whitaker arranged Kennedy a leave of absence to study toward an economics degree at Nuffield College, Oxford under 1972 joint Nobel laureate Sir John Hicks.
The Irish Experience, whilst assistant principal officer in economic policy at the Department of Finance and part-time lecturer at UCD; it would be his first book published in 1971 and variously commended as among the first academic studies of Ireland's twentieth-century economy, and his careful consideration of statistics.
When published that October, The Way Forward belatedly encouraged fiscal restraint, but was criticised, including by senior Department of Finance officials, as being "highly optimistic" because it did not foresee an increase in taxes, for example.
He continued to influence government policy toward small business supports and chaired a working group on the Irish punt's 10% devaluation in 1993 on the back of speculative attacks against the British pound (Black Wednesday) and Italian lira.
[17] He retired as director of the ESRI in October 1996 but continued for some years as a part-time researcher; his last publication with the institute, Reflections on the Process of Irish Economic Growth, was read before the Statistical and Social Inquiry Society of Ireland 26 April 2001.
It will be clear that a satisfactory long-term resolution of the inflation-unemployment dilemma will involve an extension of the conventional boundaries of economics to take account of social and political variables – not only at national but also at international level.
[1][2] He proposed many ideas for reducing the deficit, including a balanced budget amendment to the Constitution; this, as well as supporting Ireland's membership of the European Exchange Rate Mechanism, "reflected an ethos of self-denial that found little purchase in an emerging consumer society", according to Clavin.
While taking night classes at UCD, Kennedy befriended professor and Independent Seanad member George O'Brien, who wrote comforting letters for when he was recuperating from tuberculosis.