This interesting and unusual name derives from the Norman personal name Serlo, or Sarli and was probably originally a byname from the Olde Norse 'Sorli', a kin to the Olde English 'Searu' meaning armour. It is therefore likely to be a descriptive name for a latter day bodygaurd, a 'defender or protector'. There are various spellings in the modern idiom, for example, Searl, Serle, Serrell, Sarl and Sarle. It is interesting to note that the personal name found in Cambridgeshire in 1275 still flourishes there as a surname. The first recorded spelling of the family name is shown to be that of Matilda Sarle, which was dated 1275, in the Rotuli Hundredorum, Cambridgeshire, during the reign of King Edward 1, 1272 - 1307, known as 'The Hammer of the Scots'. 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.