Registrar-General's Statistical Review of England and Wales, Text volumes 1921 to 1939 and Tables Part 1 (Medical) 1926, Internet Archive scans. Values in el/england_wales_1916_1937.csv
How it connects
This book or paper is where we read about
England and Wales 1919 to 1937: sleepy sickness peaked in 1924 (5,039 cases), not after the 1918 flu