Complex sentence: Alexander died in 1944 and the death duties proved crippling to Geoffrey: in 1949 he sold the castle and 3,480 hectares (8,600 acres) of the lands to the Ashdale Property Company, retaining a tenancy of the castle for himself.
Split into simpler sentences: Alexander died in 1944, and the death duties proved crippling to Geoffrey. In 1949 he sold the castle and 3,480 hectares (8,600 acres) of the lands to the Ashdale Property Company, retaining a tenancy of the castle for himself.