[1] After being restricted to reserve team football for the entirety of the 1926–27 campaign, McDonagh made his professional debut on 24 September 1927, scoring two goals in a 4–2 win at home to Clapton Orient.
He made a further eight appearances for the team, before being dropped in early December and despite the sales of fellow forwards Eric Brook and Fred Tilson to Manchester City, McDonagh could not regain his place in the side.
[1] McDonagh subsequently moved to Football League Third Division North outfit Nelson in the summer of 1928 and played his first game for the club in the 1–5 defeat away at Southport on 8 September 1928.
During the opening months of the season, he was in competition with fellow Scot Buchanan Sharp for the inside-right position, and never managed to cement a place in the team.
[3] In the summer of 1935, McDonagh had a trial with Workington but was not offered a contract and subsequently had a spell in Ireland with Sligo Rovers.