1921 History of shipping clerks

My Grandmother Lillian Lettuce Henwick and her father Harry Henwick worked in Tilbury in 1921. Lillian was a clerk and her father a Chief Shipping Clerk. I would be very interested if anyone has information about how the company worked in those days and where they would have worked from. Lillian married in 1921 and I believe left to work in the Cable Factory in Greenwich with her husband Richard Gidley.