Names are often not what they seem and this is a good example. Mould(s) - the plural being 'Son of', is a pet form of the medieval female name Maud, itself a pet form of the ancient 'Malilda' - a Saxon name of the pre 7th century. William I wife Matida was apparently known as 'Mold', which may account for the popularity of the surname. In the modern idiom there are some thirteen spellings including Maud, Mahood, Malt, Mold, Mowat etc. Basically the name is Norman French, and appears several times as a personal name in the Domesday Book of 1086. The first recorded spelling of the family name is shown to be that of Hugh Mold which was dated 1275, The Hundred Rolls of Worcester 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.