The youngest of three sons (by the first marriage) of the vicar of Desertserges, Longfield was born near Bandon in 1810. His grandfather, John Longfield of Longueville (1741-1815), represented Mallow in the Irish parliament, 1790-1800, and, as a supporter of the Union, at Westminster, 1801-02.
After excelling as an undergraduate at Trinity College, Dublin, Longfield was called to the bar in 1834 and established a practice in Dublin, though he was also a landlord in the neighbourhood of Skibbereen, county Cork.
Thereafter Longfield returned to his legal practice and published several legal works, chiefly on the law of landlord and tenant, and was appointed Queen’s Counsel in November 1852.
An active member, Longfield made 200 contributions to debate in six years. Like many Irish Conservatives, he was a critic of the national education system, arguing that ‘it did not possess the confidence of the Protestant community’. In 1860 he called for the English system of denominational education to be extended to Ireland, and opposed legislation which proposed to open endowed schools to Dissenters.
Longfield took a keen interest in electoral reform. In March 1860 he gave evidence on the administration of parliamentary elections in Ireland to the select committee on the 1854 Corrupt Practices Prevention Act.
In 1861, Longfield helped to prepare measures to regulate Irish markets (sitting on the relevant select committee), and to repatriate the destitute Irish residing in England and Scotland.
In 1863 Longfield attacked the government’s Irish salmon fisheries bill, introducing his own measure to assimilate the Irish and English laws and, having served on the select committee on the Irish fisheries bill, took an active part in the subsequent debate.
Longfield served on the 1863 select committee on Thames conservancy, having earlier sat on committees to consider bills for Leith harbour and docks, the transport service, burials, and the registration of births, deaths and marriages in Ireland.
In spite of his prodigious activity at Westminister, Longfield’s standing in his own constituency suffered. His defence, in 1861, of proprietorial rights regarding the notorious Derryveigh evictions in Donegal, his justification of the allegedly sectarian practices of the Royal Hibernian Military School, and his absence from the early and important divisions on the Catholic oaths bill meant that his suitability to represent ‘a Catholic and Liberal constituency’ was called into question. In February 1864, Longfield was further criticised for donating funds to an organisation regarded by the Irish Liberal press as a promoter of the ‘propaganda of Souperism’.
Shortly after Derby’s return to power in July 1866 he was appointed government law adviser at Dublin Castle.
