Retirement Following the defeat of his government, Costello returned to the bar. In 1959, when Richard Mulcahy resigned the leadership of Fine Gael to James Dillon, Costello retired to the backbenches. Costello could have become party leader had he been willing to act in a full-time capacity.John A. Costello, Compromise Taoiseach, Anthony J. Jordan, Westport Books, 2007, pp. 163–64, . He remained as a TD until 1969, when he retired from politics, being succeeded as Fine Gael TD for Dublin South-East by Garret FitzGerald, who himself went on to become Taoiseach in a Fine Gael-led government.
retirement following the defeat of his government costello returned to the bar in 1959 when richard mulcahy resigned the leadership of fine gael to james dillon costello retired to the backbenches costello could have become party leader had he been willing to act in a full-time capacityjohn a costello compromise taoiseach anthony j jordan westport books 2007 pp 163–64  he remained as a td until 1969 when he retired from politics being succeeded as fine gael td for dublin south-east by garret fitzgerald who himself went on to become taoiseach in a fine gael-led government