Síle de Valera Dublin, where she qualified as a career guidance teacher. De Valera comes from a famous political family; she is the granddaughter of Éamon de Valera, the founder of Fianna Fáil, former Taoiseach and third President of Ireland. She is a niece of the former TD Vivion de Valera and is a first cousin of Teachta Dála Éamon Ó Cuív. De Valera was first returned to Dáil Éireann in the Fianna Fáil landslide victory at the 1977 general election. She was elected for the Dublin County Mid constituency, which included the Tallaght area of County Dublin, being the youngest TD elected
Éamon de Valera with the support of at least seven independents. The result was the First Inter-Party Government, with John A. Costello of Fine Gael as its compromise candidate for Taoiseach. Costello was duly nominated, consigning de Valera to opposition for the first time in 16 years. The following year, Costello declared Ireland as a republic, leaving partition as the most pressing political issue of the day. De Valera, now Leader of the Opposition, left the actual parliamentary practice of opposing the government to his deputy, Seán Lemass, and himself embarked on a world campaign to address the issue of partition. He visited