This is a medieval nickname which originally derves from the French Guillaume, itself a variant of the Olde German William, and usually found as Gillkin (Son of Gill) with Ghilks, Gilkes and Gilks, being the shortened versions. Introduced after the 1066 Norman Inavasion 'William' in its many forms became the fore most name of the early medieval period, the variants literally running into hundreds of spellings. The name development to Guille 110, to Gilkoc 1270, to Gilkinuse 1305, To Eleneor Gilks 1753, Marnell to Samuel Wattes, London. The first recorded spelling of the family name is shown to be that of Cecilia Gilkoc. which was dated 1273, The Hampshire Hundred Rolls. during the reign of King Edward I, The Hammer of the Scots, 1272 - 1307. 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.