McDonagh started his career at his hometown club Rotherham United, and spent a month on loan at Manchester United in 1973, before joining Bolton Wanderers, initially on loan, taking over from the recently departed Barry Siddall.

An ever-present during the Second Division Championship-winning side of 1977–78, he set a club record of conceding only 33 goals in a 42-match season.

Within a year Neville Southall had come through the ranks at Everton and McDonagh found himself back at Bolton.

Another relegation followed in 1982–83, even with McDonagh managing to score a goal, and he moved on to Notts County for two seasons before wandering around a further six English clubs as well as teams in the USA.

[3] O'Neill then appointed him to the same role with the Republic of Ireland national team in November 2013.