Bentwich was then appointed an inspector of schools for the Mandate Government, and from 1943 to 1948 was an assistant director of the Department of Education.
[1] In 1948, following the resignation of Arthur Biram, Bentwich was appointed as his replacement as principal of the Hebrew Reali School in Haifa, a position he held until 1955.
Bentwich was a leader of the Amanah (Covenant) group, established to study and promote new interpretations of Judaism.
His eldest brother, Norman Bentwich, was a leading British lawyer, who also spent much of his professional life Mandate Palestine and Israel.
Another sibling was Thelma Yellin, a renowned cellist and active pioneer of the musical life of Mandate Palestine.