Radical lawyer

Returning to Ireland, McNally developed a successful career as a barrister in Dublin.^[6] He developed an expertise in the law of evidence and, in 1802, published what became a much-used textbook, The Rules of Evidence on Pleas of the Crown.^[7] The text played a crucial role in defining and publicising the beyond reasonable doubt standard for criminal trials.^[7]

Not long after returning to Ireland, he became involved in radical politics, having already, in 1782, published a pamphlet in support of the Irish cause.^[6] He became Dublin's leading radical lawyer of the day.^[8] In 1792, he represented Napper Tandy, a radical member of the Irish Parliament, in a legal dispute over parliamentary privilege.^[6] In the early 1790s, McNally became a founder member of the United Irishmen,^[9] a clandestine society which soon developed into a revolutionary Irish republican organisation.^[10] He ranked high in its leadership and acted as the organisation's chief lawyer, representing many United Irishmen in court.^[11][12] This included defending Wolfe Tone and Robert Emmet, the leaders of the 1798 and 1803 rebellions respectively, at their trials for treason.^[13] In 1793, McNally was wounded in a duel with Sir Jonah Barrington, who had insulted the United Irishmen.^[6] Barrington subsequently described McNally as "a good-natured, hospitable, talented and dirty fellow".^[6] John O'Keeffe described McNally as having "a handsome, expressive countenance and alive sparkling eyes".^[14]

Informer and government agent

After his death in 1820, it emerged that McNally had for many years been an informant for the government, and one of the most successful British spies in Irish republican circles that there has ever been.^[13] When, in 1794, a United Irishmen plot to seek aid from Revolutionary France was uncovered by the British government, McNally turned informer to save himself,^[13] although, subsequently, he also received payment for his services.^[15] McNally was paid an annual pension in respect of his work as an informer of £300 a year, from 1794 until his death in 1820.^[8]

From 1794, McNally systematically informed on his United Irishmen colleagues, who often gathered at his house for meetings.^[5] It was McNally that betrayed Lord Edward FitzGerald, one of the leaders of the 1798 rebellion, as well as Robert Emmet in 1803.^[15] A significant factor in the failure of the 1798 rebellion was the efficacious intelligence provided to the government by its agents.^[16] McNally was considered to be one of the most damaging informers.^[16]

The United Irishmen represented by McNally at their trials were invariably convicted^[15] and McNally was paid by the crown for passing the secrets of their defence to the prosecution.^[17] During the trial of Emmet, McNally provided details of the defence's strategy to the crown and conducted his client's case in a way that would assist the prosecution.^[8] For example, three days before the trial he assured the authorities that Emmet "does not intend to call a single witness, nor to trouble any witness for the Crown with a cross-examination, unless they misrepresent facts… He will not controvert the charge by calling a single witness".^[8] For his assistance to the prosecution in Emmet's case, he was paid a bonus of £200, on top of his pension, half of which was paid five days before the trial.^[8]

After McNally's death, his activities as a government agent became generally known when his heir attempted to continue to collect his pension of £300 per year.^[17] He is still remembered with opprobrium by Irish nationalists. In 1997, the Sinn Féin newspaper, An Phoblacht in an article on McNally, described him as "undoubtedly one of the most treacherous informers of Irish history".^[18]

Playwright and lyricist

McNally was a successful dramatist and wrote a number of well-constructed but derivative comedies, as well as comic operas.^[19][20] His first dramatic work was The Ruling Passion, a comic opera written in 1771,^[19] and he is known to have authored at least twelve plays between 1779 and 1796 as well as other comic operas.^[20] His works include The Apotheosis of Punch (1779), a satire on the Irish playwright Richard Brinsley Sheridan, Tristram Shandy (1783), which was an adaptation of Lawrence Sterne's novel, Robin Hood (1784), Fashionable Levities (1785), Richard Cœur de Lion (1786), and Critic Upon Critic (1788).^[19]

He also wrote a number of songs and operettas for Covent Garden.^[21] One of his songs, Sweet Lass of Richmond Hill, became very well-known and popular following its first public performance at Vauxhall Gardens in London in 1789.^[21][22] It was said to be a favourite of George III^[23] and popularised the romantic metaphor "a rose without a thorn", a phrase which McNally had used in the song.^[24]