The eldest son of Captain Matthew Le Geyt, RN, of Mont à L`Abbé and nephew of the Lieutenant-Bailiff, Sir John Dumaresq, he was Seigneur de La Houguette until 1812, Lieutenant-Colonel and Inspector of Militia Artillery and Adjutant, RJM. He was the first poet of the Jersey Norman-French Language since Wace, in the early 12th century.
Le Geyt was commissioned into the Jersey Militia Artillery in 1794, shortly before his 17th birthday, but transferred into the Regular Army, being commissioned into H.M. 9th Regiment of Foot, (later called The Norfolk Regiment), before becoming a Lieutenant in 1797. Tiring of garrison life and endless training and recruiting, he returned in the early 1800s to Jersey. In the 1815 Military Census of Jersey, he was a "Lieutenant of Troopers", referring to the short-lived Jersey Cavalry. In 1828, he was Battalion Major, RJM, then Adjutant; Inspector of Artillery in 1837, he became by 1840, Lieutenant-Colonel, RJMA (Royal Jersey Militia Artillery). In 1812, however, he had been obliged to sell his fief and four hundred year-old home, with its obligation to furnish the militia with four muskets, as well as his 80 vergées of land. Creditors, sixty-one in number, being still unsatisfied, he was in 1822 declared bankrupt. He joined the Freemasons in 1815 and was for a while a coal merchant before becoming, from his son Matthieu`s Marriage Register entry, an "Officer of Excise" for the remainder of his working life.
As a dialect poet, John Kelleher writes, in Triumph of the Country, (John Appleby Publishing, 1994), 252-3, "His subject matter was local incidents brought to a more lofty plane...Le Geyt`s work established a mould which would determine much of the dialect work for the rest of the century...He was essentially a cultural poet and not a nationalist writer."
Although from St Helier, he had at one-time lived in Trinity, where he was a Vingtenier, returning afterwards to his native parish. He married in 1805 Rachel Poingdestre, daughter of Pierre, of Mont à L`Abbé, by whom he had a surviving son and three daughters.
He was present at the laying of the foundation stone of the Victoria Pier in 1841, and can be seen in his dark blue artillery uniform behind the model of a sailing vessel, in an oil on canvas painting of that occasion.