Upton is born in Kilrush, County Clare and educated at St. Flannan’s College in Ennis, at University College Galway, and at University College Dublin (UCD) where he receives a doctorate in veterinary medicine. He then works as a lecturer.
Upton is first elected to public office as a Labour Party member of Dublin County Council for Terenure at the 1991 Irish local elections, where he serves until the Council’s abolition in 1994, and then as a member of South Dublin County Council until 1999.
Upton unsuccessfully contests the Dublin South-Central constituency at the 1989 Irish general election. However, he is then elected to the 19th Seanad on the Agricultural Panel, and becomes the Labour Party’s leader in Seanad Éireann.
At the 1992 Irish general election, Upton stands again in Dublin South-Central, and in Labour’s “Spring Tide” surge at that election, he tops the poll with nearly 12,000 first-preference votes, a remarkable 1.48 quotas. He is re-elected at the 1997 Irish general election with a considerably reduced vote.
In the 28th Dáil Upton is appointed as Labour’s spokesperson on Justice, Equality and Law Reform. A leading critic of Labour’s 1999 merger with the Democratic Left, he nonetheless becomes the party’s spokesman on communications and sport after the merger.
Upton is a member of the Parliamentary Assembly of the Council of Europe in 1994–95.
Upton dies suddenly of a heart attack on February 22, 1999 at the UCD Veterinary College, where he is an occasional lecturer. He is taken to St. Vincent’s Hospital and his death is officially confirmed. He is survived by his wife and their four children. Politicians of all parties pay glowing tributes to him for his outspoken but “erudite and incisive” contributions to politics and to Irish culture.
Following Upton’s death, the University College Dublin branch of the Labour party is named in his honour due to his involvement with the college. It has since been renamed to honour the Spanish Civil War veteran Charlie Donnelly.