He was born the eldest son of John and Eleanor (née Lucas) Longfield of Longueville.
[1] He was appointed High Sheriff of County Cork for 1833–34,[2] an office that had also been held (1829–30) by his father.
Having successfully petitioned against the re-election in January 1835 of the radical Repeal MP Feargus O'Connor, on the grounds that O'Connor failed the property qualification then required of MPs, Longfield took the seat on 5 June.
[1] A relation, also named Richard Longfield (1734–1811), had sat in the Irish House of Commons for Charleville in County Cork (1761–68), for Cork City (1776–83 and 1790–96), and for Baltimore, County Cork (1783-1790), before becoming the first and last holder of the titles of Baron Longueville and Viscount Longueville in the Irish peerage; he had also been High Sheriff of the County (1758–61).
[3] Another relation, Mountifort Longfield, was the last to hold the Irish seat of Cork City before it ceased to exist with the Act of Union 1800.