This most interesting surname is of Old Gaelic origin, and is the Anglicized form of the Gaelic "O'Loideain", which is composed of the Gaelic prefix "O", male descendant of, and the personal name "Loidean", of uncertain etymology; hence "the male descendant of Loidean". Lydon, a variant form, belongs almost exclusively to Counties Galway and Mayo, and is the most numerous Anglicized form of "O'Loideain". Leyden itself is found chiefly in Connacht and Co. Clare, and another variant Liddane is established in Co. Clare. Ludden is another variant occasionally recorded in Co. Galway. None of these surnames occur, except occasionally, in any part of the country east of the Shannon. The Annals of Loch Ce record the death of the first recorded namebearer (see below), who it is said was "a paragon of piety and learning". Ann Liddin was christened at St. Nicholas Within, Dublin, on April 9th 1710; Adam, son of Walter and Emma Leyden, was christened on September 8th 1793, at St. Anne's, Soho, Westminster, in London; and Alice Lyden married Constantine O'Hara in Galway, in August 1806. The first recorded spelling of the family name is shown to be that of Abbot O'Lotain, which was dated 1216, in the "Annals of Loch Ce", during the reign of King John of England, known as "Lackland", 1199 - 1216. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.