O’Brien was born in Dublin, the son of Sir Timothy O’Brien, a wealthy Dublin merchant who sat for Cashel, 1846-62. In 1844 he became a barrister and served as secretary to his father, then lord mayor of Dublin. A member of the city corporation, he attended upon the queen during her visit to Ireland in May 1845.
O’Brien later confessed that early in life he had been ‘dazzled by the genius of Sheridan, the eloquence of Fox, and the efforts of their compatriots in favour of Catholic independence and public liberty’, but declared that subsequent events had induced in him ‘a feeling of repugnance … towards that animal called a Whig’.
Having attested to his ‘thorough independence of any governments’, he joined the Independent Irish party, attending and accepting the resolutions of the tenant-right and religious equality conferences that autumn, and was present at the free trade banquet at Manchester, 2 Nov. 1852.
As the son of one of Ireland’s leading whiskey merchants, O’Brien formed close ties with the country’s distillers, and consistently supported the removal of restrictions on the spirit trade. In June 1853 he contended that Irish distillers were disadvantaged in comparison with those of Scotland, and argued that an increase in excise duty on spirits would only increase illicit distillation.
O’Brien was a staunch and articulate defender of the rights and reputation of Catholics within the United Kingdom, and encouraged the reform of Dublin University, where he had been a student.
O’Brien backed the government over the Crimean War and attacked critics of the enlistment of foreigners bill, 22 Dec. 1854, for believing that it was ‘impossible for a German to sympathise in the cause that involved the liberty of Europe, and to fight for it’.
Like his father, O’Brien remained faithful to the Independent Irish party until 1854. Thereafter his allegiance was regarded as ‘doubtful’, and it was later said that it was ‘utterly impossible to imagine [him] a member of a pledge-bound party’.
A man of ‘considerable reading’, O’Brien believed that the system of Irish National Schools had provided Catholics with ‘a capital education’, while affording them the ‘spiritual instruction … necessary to their eternal salvation’.
O’Brien supported Palmerston on Cobden’s motion on Canton, 3 Mar. 1857, and, although his commitment to act ‘with the independent opposition’ was viewed with scepticism, he was returned unopposed for King’s County at the following general election.
In July 1858 O’Brien unsuccessfully tried to postpone the Dublin police bill, accusing the government of ‘acting on the old Orange principles’ by introducing ‘a military instead of a civil system of police’ to the city.
O’Brien continued to feel strongly about the land question.
O’Brien was narrowly returned again at King’s County after a four-way contest in 1859.
Upon succeeding to his father’s baronetcy in 1862, O’Brien came into possession of land in Cork and Queen’s county. He was ‘a general favourite’ at the Reform Club, where he was ‘full of quaint stories of Irish life’.
At the risk of losing popularity in his constituency, O’Brien publicly denounced the ‘unhappy and disgraceful Fenian conspiracy’, arguing that it risked frustrating the country’s chances of prosperity, and praised ‘the spirit of Christian fearlessness’ with which senior Catholic clergymen had prevented the insurrection from taking ‘deeper root in the country’.
In 1867 O’Brien assisted with a bill to compel railway companies to provide an efficient means of communication between the guards and passengers of railway trains.
In December 1867 O’Brien joined a deputation to the treasury to request the institution of a department of science and art in Dublin, and the following April joined the platform at a public meeting of the National Reform Union, chaired by Earl Russell, which endorsed Gladstone’s resolutions in reference to the Irish Church.
