Upper-Class Fertility Collapse Hurt Britain

From about 1850 to the 1920s-30s, an astonishingly low fertility (one to one-and-a-half children per family for 50-60 years) emerged among the British upper classes, compounded by 20% of upper-class men dying in World War I, dramatically shrinking the relative size of the upper class and offering a potential explanation for Britain's lukewarm economic performance and declining entrepreneurship since WWI.