He attended the prestigious Xavier College, excelling at rowing, cricket and football.
[2] McGillicuddy enrolled at the University of Melbourne in 1911, studying medicine, and while in his first year he made his VFL debut with the University team in Round 13, 15 July 1911, against Carlton Football Club at Carlton's home ground Princes Park.
[3] University lost by 44 points and McGillicuddy was omitted from the University side until Round 16, when he returned to play against Collingwood at the Melbourne Cricket Ground (MCG), which Collingwood won 14.14 (98) to 0.9 (9).
Following his graduation from Medical School, Dr McGillicuddy enlisted in World War I and served as captain in the Australian Army Medical Corps Hospital Transport Corps at Suez Canal in 1917–18 as part of the Sinai and Palestine campaign but was discharged due to chronic cough.
[5] Upon his return from war McGillicuddy married stage performer Goodie Reeve and moved to Queensland, where their daughter Patricia Mary "Yuki" was born.