This interesting and unusual name, recorded in English church registers from the late 16th Century under the variant spellings Dedham, Dedam, Deddum, Dowdam etc., is of locational origin from a place in Essex called Dedham. The placename, recorded as Delham in the Domesday Book of 1086, as Dedham in the 1165 Pipe Rolls of that county, and as Didham in "Feudal Aids", dated 1428, is so called from the old English pre 7th Century personal name Dydda, plus "ham", a village, estate or homestead. On February 3rd 1578 John Dedam and Ruthe Heath were married in St. Dunstan's in the East, London and on May 30th 1614 Mary Ann Deddum married a John Thornton in St. Olave, Hart Street, London. Further recordings include the marriage of John Dowdam to Sara Hamblton (London, 1661), and the marriage of Edwin James Diddams to Emma Harris in Canterbury, Kent, on July 28th 1667. The final "s" on the name preserves the old English genitive ending i.e. "of Didham". The first recorded spelling of the family name is shown to be that of Richard Dedham, (marriage to Catherine Baker), which was dated 1576, in the "Dedham church registers", Essex, during the reign of Queen Elizabeth 1, known as "Good Queen Bess", 1558 - 1603. 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.