Anglo-Saxon England ended at the Battle of Hastings in 1066, after which William, Duke of Normandy, was crowned King of England.

William gave the country a strong central government. One instrument of this control was the Domesday Book of 1086, in which Brill is mentioned as having 19 villeins or serfs, 13 bordars or cottages and 2 slaves. During Norman times, Brill became the administrative centre of the surrounding royal forest of Bernwood (originally known as Brill forest) in which the Norman and Plantagenet kings regularly hunted deer and wild boar.

It has been calculated that, in the time of Henry II, Bernwood Forest covered at least 40 square miles, or 90,000 acres. The term "forest" in this context does not necessarily mean an area of continuous trees. Old maps of Bernwood Forest show much the same chessboard pattern of fields and woods that persist today except there were trees growing on what is now the open grass and bracken of Brill Common. Forest, in this context, was basically a technical lawyer's term that meant that the area in question came within the jurisdiction of the Forest Law, a Norman innovation. The object of the Forest Law was to ensure the preserving of all red and fallow deer.

One of the special privileges of living in a forest town like Brill was the grazing and firewood available at everybody's back-door, although both rights were carefully defined and strictly limited