In 1918 Whitehead's academic responsibilities began to seriously expand as he accepted a number of high administrative positions within the University of London system, of which Imperial College London was a member at the time. He was elected Dean of the Faculty of Science at the University of London in late 1918 (a post he held for four years), a member of the University of London's Senate in 1919, and chairman of the Senate's Academic (leadership) Council in 1920, a post which he held until he departed for America in 1924. Whitehead was able to exert his newfound influence to successfully lobby for a new history of science department, help establish a Bachelor of Science degree (previously only Bachelor of Arts degrees had been offered), and make the school more accessible to less wealthy students.

When did Whitehead accept administrative positions?