He gained notoriety for his celebrated lawsuit for adultery against his former friend Sir John Piers, who had seduced Cloncurry's first wife, Elizabeth Georgiana Morgan.

He purchased an estate near Rouen; but finding that in France the Catholic Church "made invidious distinctions in the distribution of her honours among the faithful", not only returned to Ireland but conformed to the established Anglican communion.

While at Trinity he was active in the Historical Society,[4] the club formed by Edmund Burke, in which, preceding Lawless, the future United Irishmen Wolfe Tone and Thomas Addis Emmet had engaged in their first debates.

While he little sympathises with "the cause of royalty" for which they had suffered, he was moved by the tales of the betrayal and dispossession that, following the Williamite War in Ireland, had forced their fathers to seek fortune abroad.

[7] Lawless returned to Ireland in the spring of 1795 after hopes of reform had been dashed by the recall of William Fitzwilliam who, Lord Lieutenant, had spoken in favour of Catholic Emancipation.

[9] Composed by William Drennan, this committed Lawless to forward a "union of power among Irishmen of every religious" so as to attain "an impartial and adequate representation of the Irish nation in parliament".

[10] Reflecting the growing impatience and insurrectionary tenor of the movement, a convention in Belfast had, the previous month, adopted amendments dropping the reference to the Irish Parliament and swearing members to secrecy.

[11][12] Lawless played an open, constitutionalist, role, publicly protesting what he knew to be Prime Minister William Pitt's undeclared Irish policy: the abolition of the Dublin parliament and the incorporation of Ireland into a united kingdom with Great Britain.

[2] Lawless personally administered the society's new test to Father James Coigly, who was to be the executive principal agent in attempts to coordinate an insurrection with radical circles in England and with the French directory.

Lawless used his time in Rome to purchase works of art being sold off by Italian nobles under pressure from Napoleon's oppressive taxation, and sent four shiploads to Ireland for the refurbishment of Lyons House.

They included a statue of Venus excavated at Ostia and three pillars from the palace of Nero originally looted from Egypt, but other artefacts were lost when the third shipment sank off Wicklow Head.

He employed the Italian painter Gaspare Gabrielli to paint the frescoes, a fact which assumed great significance during his subsequent action against Sir John Piers for adultery.

[17] In 1807 Lawless brought a sensational action for criminal conversation against Sir John Bennett Piers, 6th Baronet, a neighbour and school friend,[18] whose dalliance with Lady Cloncurry had been witnessed by the painter Gaspare Gabrielli while he was at work painting frescoes at Lyons House.

The lurid details of the case aroused huge public interest, in particular the barely credible evidence that the couple had been too preoccupied to notice that the painter was up a ladder in the same room.

[2] Lawless ran for parliament but remained prominent as a magistrate (he helped introduce public petty sessions in Kildare to make the legal system more accessible to the people) and as a "tithe abolitionist".

[21] Daniel O'Connell, despite their frequent and bitter political differences, praised Cloncurry warmly: "In private society, in the bosom of his family, the model of virtue, in public life worthy of the admiration and affection of the people".