This ancient and distinguished surname, borne by the Earls of Salisbury and Exeter, the Barons Burghley, and the Viscounts Wimbledon, is of Old Welsh origin, and derives from the Old Welsh male given name "Seisyll(t)", apparently ultimately from the Latin "sextilius", a derivative of "sextus", "sixth(-born)". This name was borne by various saints and popes in the early centuries of the Christian era, and subsequently adopted in their honour. Early bearers of the Welsh form of the name were Seisyll ap Clydog (flourished 730), first King of joint Ceredigion and Ystrad Tywi, and Seisyllt ap Clydog (flourished 925), Lord of Gwynedd. The name is well recorded in the Welsh border counties, appearing as "Saissil" and "Seisil" respectively in the Domesday Book of 1086 for Herefordshire, and the 1188 Pipe Rolls of Shropshire. The Cecils were originally Welsh gentry, and David Cecil, grandfather of Lord Burghley, who had espoused the cause of Henry Tudor, came to court in London after the latter became king in 1485. William Cecil, Lord Burghley (1520 - 1598), was lord high treasurer, 1572 - 1598, and chief adviser to Elizabeth 1. His eldest son, Thomas, became first Earl of Exeter, and Robert, another son, was created Earl of Salisbury in 1605. A Coat of Arms held by the Cecil family is a shield divided per barry of ten silver and azure, over all six black escutcheons, three, two, and one, each charged with a lion rampant of the first. The first recorded spelling of the family name is shown to be that of William Seisil, which was dated 1205, in the "Pipe Rolls of Herefordshire", during the reign of King John, known as "Lackland", 1199 - 1216. 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.