McKenna was born in Dublin, the son of a wealthy Catholic businessman, whose own father had prospered in Philadelphia the previous century. He hailed from a Monaghan family and claimed to be the eldest lineal male descendant of the last Prince of Truagh.
McKenna was narrowly defeated as a Liberal at New Ross at both the 1859 general election and a subsequent by-election in 1863, and lost to The O’Donoghue (Daniel O’Donoghue) in a stormy by-election at Tralee in February 1865.
McKenna played a controversial role during the reform crisis of 1866-7. In April 1866, McKenna’s speech in support of Lord Grosvenor’s amendment to Gladstone’s reform bill was interpreted ‘as a vote of want of confidence in the Irish administration of the Government’.
At the 1868 general election, McKenna presented himself as an ‘independent Liberal’, yet was regarded in Liberal circles as standing upon ‘the independent principles of a Catholic Tory’. He was defeated by a Gladstonian Liberal in a notoriously corrupt contest and did not claim the seat after his opponent, Christopher Wegulin, was unseated on petition.
Nevertheless, McKenna’s political fortunes revived as he re-invented himself as a home ruler. After joining the Home Government Association in September 1873, he addressed the Home Rule conference and likened the case of Ireland and England to that of Austria and Hungary. He was one of two ‘Conservative Home Rulers’ elected at the 1874 general election, and following his return in 1880 he involved himself in the land question.
McKenna died at his estate at Ardrogena, Co. Cork in 1906 and was buried in the local cemetery. His nephew, Reginald McKenna, was Liberal MP North Monmouthshire 1895-1918, and served as First Lord of the Admiralty 1908-11, Home Secretary 1911-5 and Chancellor of the Exchequer 1915-6.
