In England, at least, if "middle class" as defined as not-rich who can nevertheless expect some support from their parents and pass a nest egg down to their grandchildren, there was no real, lsubstnail, and numerous "middle class" in the twentieth century:
Neil Cummins: The Missing English Middle Class: Evidence From 60 Million Death And Probate Records: "Using a combination of old-fashioned archival research, mass scripted downloading, optical character recognition, text parsing, and sets of algorithmic programming tools, I have digitised every individual entry, 18 million records with estate values, from the Principal Probate Calendar from 1892 to 1992. To this I have added all 60 million adult English deaths.... This simple finding is quite stark: despite the great equalisation of wealth over the 20th century, most English have no significant wealth at death...
...The methodology I have applied here to constructing a new dataset can be applied to any set of images of historical records that contain consistent formatting. There are many millions of these images lying on website servers all over the world. As optical character recognition software continues to become more accurate, there is now remarkable potential for new, big data analysis in economic history...
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