This interesting name derives from Jack, a pet form of the personal name John (from the Hebrew "Yochanan" meaning "Jehovah has favoured me with a son") plus "cock", a suffix which was added to the nickname of the baptismal name to indicate the pertness of lusty and swaggering youth. The surname from this source is first recorded in the early half of the 14th century (see below). One John Jecok appears in the 1375 Court Rolls of the Borough of Colchester, and a John Jecokes in the 1381 Assize Court Rolls of Warwickshire. The development of the name is as follows: Jack-Cock was abbreviated to Jacock and this was transposed to Jeacock. In 1712 the marriage of one James Sharples and an Elizabeth Jeacock was recorded in St. James Church, Clerkenwell, London. Modern varinats of the name are shown as Jeacock(e), Jacox, Jecock, Jaycocks and Jaycox. The first recorded spelling of the family name is shown to be that of William Jacok, which was dated 1327, in the "Subsidy Rolls of Suffolk", during the reign of King Edward 111, known as "The Father of the Navy" 1327 - 1377. 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.