Mahony was of ancient Irish lineage and grew up on his father’s estate near Listowel, co. Kerry, which he inherited in 1819.
Though a Protestant, Mahony was appointed by Daniel O’Connell as parliamentary agent for the Catholic Association in 1828 during the critical period leading up to the concession of emancipation.
In society, Mahony was ‘a prime favourite for his social qualifications’ and regarded as the epitome of the ‘wealthy and fashionable attorney of the day’.
Known for his shrewdness, Mahony quickly became, as Stanley put it in 1831, ‘a prominent if recent recruit to Whiggery’.
When Mahony subsequently came forward as a candidate for Limerick city at the 1832 general election his rejection of repeal in favour of ‘conditional’ Unionism caused O’Connell to issue a ‘broadside’ calling upon the electors to reject a man he considered ‘worse than a Conservative or an Angleseyite’.
Though he lacked a seat in parliament, Mahony remained an active reformer. He regarded the want of general provision for the Irish poor as ‘the primary cause’ of the country’s disorganised state, and advocated a well-regulated system of emigration and the institution of public works as a means of employment.
In February 1838, he prepared the Cork sessions bill, which proposed to provide the county with a greater number of general sessions, and the church property (Ireland) bill, which aimed to amend the conditions of tenure of more than half a million acres of land. Neither was successful.
As a largely ‘self-taught man’ Mahony developed ‘a robust and powerful understanding’ of Irish questions and demonstrated a practical knowledge that was described as ‘rare and profound’. At his death in 1853 he was said to have anticipated many of the principal legal and social reforms of his time and was for many years an influential witness at a range of parliamentary inquiries
It was, however, in the railway industry that Mahony played his most influential and controversial role. His roles as solicitor to the Dublin and Kingstown Railroad (from 1832) and shareholders’ representative for the Dublin-Drogheda Railway brought him financial success as well as accusations of jobbery and ‘un-Irish’ behaviour.
Throughout the 1840s Mahony remained ‘an active and efficient supporter of the Whig party in Ireland’. Renowned for his hospitality, Mahony’s home was dubbed ‘the Holland House of the Irish Whigs’ and he was credited with nurturing the political ambitions of ‘more than one transmitted offshoot of the English Whig aristocracy’.
Mahony himself held almost 6,000 acres in counties Kerry, Cork, Limerick and Wicklow. He was recognized as a pioneer of improving agriculture, being praised by the Devon Commission in 1845 for the condition of his Kerry estate, which proved, so the report stated, ‘what can be done at a moderate cost in an extensive district’.
Having prepared an address of loyalty to the viceroy (which also enumerated many defects in Irish government) in April 1848, Mahony was appointed a taxing master of the Irish court of chancery that September and became clerk of crown queen’s bench in January 1849.
