In 1788, Luttrell was publicly accused in Dublin of the rape of a 12 year-old girl. Having been paid to deliver a message, Mary Neal claimed she was bundled into a brothel and there assaulted throughout the night by Luttrell. The keeper of the house, Maria Llewellyn, was charged in a case marked by accusations of witness tampering, the death in prison of Amy's mother and new-born baby sister and by the insinuation that Amy was already working as a prostitute. The affair became a "cause célèbre" with the public intervention of Archibald Hamilton Rowan (later United Irishman). To clear Mary's name he brought her to Dublin Castle to see the Lord Lieutenant, the Earl of Westmorland. Westmorland, unmoved, pardoned Llewellyn and set her at liberty. Luttrell was never asked to answer for raping May Neal. He re-entered the Westminster Parliament as Member for Plympton Erle in 1790. Then in 1796 he was made Commander-in-Chief, Ireland, and in 1798 he led the British suppression of the United Irishmen Rebellion. His command had the unusual distinction of being upbraided by his successor as Commander in Chief, Sir Ralph Abercromby for an army "in a state of licentiousness, which must render it formidable to every one but the enemy". When the "Dublin Post" of 2 May 1811 erroneously reported his death, he demanded a retraction which they printed under the headline "Public Disappointment". He purchased an estate at Painshill Park in Surrey and re-entered parliament in June 1817 as Member for Ludgershall and held the seat until his death. He briefly married Elizabeth Mullen in 1759, and had a daughter, Harriet Luttrell. This marriage was later annulled. He married Jane Boyd in 1776, but they had no children and was succeeded by his brother John.