 Early documents record the name as Diddsham, presumably for a family known as Did or Didd.In 1582–1587, a schismatic Presbyterian Christian group called the "Dedham Classis", which included dozens of members opposed to the established church, was active in north-east Essex.This group held clandestine meetings and prayer groups in and around Colchester and surrounding villages like Dedham, publishing and distributing versions of Wycliffe's Bible and various other Calvinist texts obtained from London; the Dedham Classis is the best recorded of those active in the sixteenth century.