Complex sentence: Up until 1945, Wilson was not addressed as "Dr." until two years before she retired, she retired at the age of 65 which was required by law however, she kept her office at the Survey and continued her work up until her death.
Split into simpler sentences: Up until 1945, Wilson was not addressed as "Dr." until two years before she retired. She retired at the age of 65 which was required by law, however she kept her office at the Survey and continued her work up until her death.