This interesting name may perhaps be an English variant of either "Langan" or "Lenihan", which are the Anglicized versions of the Gaelic names "O'Longain" and "O'Lennachain", respectively. The former name probably derives from "long", tall or "long", ship, a nickname for a seafarer, and the latter of unknown origin. O'Leannachain was originally the name of an Irish sept situated in Roscommon, while two distinct septs of O'Longain existed, one in Co. Mayo, a branch of the Ulster sept of County Armagh; the other in Counties Cork and Limerick, who were erenaghs (lay lords) of Ardpatrick, County Limerick and Patrician stewards of Munster (now called long). The names Langan or Lenihan were introduced to Britain by Irish famine immigrants (1845-1847) and probably through differences in pronunciation or because they wanted the name to sound English, became "Lanahan". One Susan Lanahan, aged 18 yrs, arrived on May 30th 1845, at New York aboard the "Mersey", from Liverpool. Mary Lanahan also aged 18yrs, arrived there aboard the "Empire", from Liverpool on April 7th 1847. At St. George the Martyr, London, Margaret Lanahan was christened on May 4th 1849. The first recorded spelling of the family name is shown to be that of Maelciaran O'Lenechan, which was dated 1249, a priest mentioned in the "Annals of Loch Ce", during the reign of de Burgo, Norman Conqueror of Ireland. 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.