It is believed that the name Grimethorpe originates from "Grim's Torp", a mixture of Anglo-Saxon and Viking names, meaning a torpor hamlet owned by a Viking named Grimey. Grimethorpe is at the foot of the hill upon which is the village of Brierley. In fact, Grimethorpe was likely named such as a Norse farm built close to Brierley village. Following the Norman conquest, the Brierley-Grimethorpe area came under the rule of the De Laceys of Pontefract, with a local Saxon owner. In 1066, this owner was Ernui who was said to have six carucates of land at Brerelia and Hindelia, valued at forty shillings. (A carucate was as much land as could be ploughed in one year by one plough and eight oxen. An acre was as much land as could be ploughed in one day by one plough and a pair of oxen.)