This interesting and curious surname is of Old Scandinavian origin, and is of locational derivation from a place called Clitheroe, a municipal borough and market-town near Blackburn in Lancashire, which was recorded as "Cliderhou" in 1102 in the Lancashire Charters, and as "Clitherow" in the Yorkshire Charters of 1124. The placename is composed of the Old Norse "kliethra", song-thrush, and "haugr", hill. The initial element may alternatively be an Olde English pre 7th Century "clyder", meaning loose stones. During the Middle Ages, when migration for the purpose of job-seeking was becoming more common, people often used their former village name as a means of identification, resulting in a wide dispersal of the name, in a number of spellings. Variants of the surname include Clitheroe, Clitherow, Cleatherow and Cluderay. Robert Cletherowe is recorded in the Register of the Freemen of the City of York in 1439; while Elisia Cliderowe married Jacobus Houlker in 1544, at Whelley, Lancashire; and Annes Clithero was christened in 1548, at Kirkham, Lancashire. In London the christening of Thomas, son of Benjamin Clethro, was recorded at St. Botolph's, Bishopsgate, on June 24th 1621. A Coat of Arms granted to a Clitherow, who was Lord Mayor of London in 1635, depicts a silver shield on a red chevron between three black eagles displayed, five gold annulets. The first recorded spelling of the family name is shown to be that of Thomas de Cliderhou, which was dated 1176, in the "Pipe Rolls of Yorkshire", during the reign of King Henry 11, known as "The Builder of Churches", 1154 - 1189. 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.