The Normans
It is easy to define the early history of the area surrounding Belchamp Walter with reference to the Normans. In keeping with many other towns and villages throughout the country how the area was recorded in Domesday is often the first fact that is quoted. Domesday has Belchamp Walter as " The Land of Aubrey de Vere".
However, the influence of the de Veres in the local area is not in dispute. The fact that they are the family that assisted the Conqueror in the 1066 invasion is probably not true. The de Veres are reported as being related to William I and that in itself would explain their "holding" of the land. The appointment of Chamberlain is more likely to have been made by Henry I or the Empress Matilda in the early 12th century.
Anglo-Saxon Chronicle
This seems to be the "source" document for a lot of the Medieval Historians.
According to Wikpedia:
Split Loyalty
After conquest there were many Anglo-Norman lords that had possesions on both side of the channel. Not only did this make the countries (England and Normandy) difficult to govern but there were many split loyalties.
When William returned to Normandy he left his half brother, Bishop Odo and William FitzOsbourne in charge.