You said that evidence that inequality grew with Thatcher was biased and you also said, without evidence, that the wealth gap in 1920’s was much bigger than in 1979. You also said that other evidence of inequality under Thatcher was flawed, “no cigar” was your term along with other sarcastic comments about a “nice graph”
It was a general trend after WW1 and especially after WW2 in the west to move towards more democracy, more freedoms and lower income inequality. At least the income inequality trend reversed after the oil crisis and other economical issues of the 1970s which ushered in neoliberalism
This link only compares recent times to 1938, and not the 1920s but I think it still shows the post-war change that happened:
https://equalitytrust.org.uk/how-has-inequality-changed
Some years ago I saw a Youtube video of a presentation where an economist, presented a thesis that economic macro-trends tend to last for something like a generation until they become unworkable and then they are ripe for a crisis that forces them to change. I have not been able to find the video again.
The deflationary economy of the late 1800s could not cope with the population growing faster than the gold reserves and the crisis that ultimately ended that period was WW1 - states needed to go away from the gold standard or become bankrupt.
After WW2, social democracy was in vogue in the west, even in the US where taxes were high and a father with a blue collar job could support his family and afford to build a house with the wife staying at home with the kids. Ultimately the productivity suffered and when the oil crises hit, there was again a shift.
Since the 1980s, we have had neoliberalism, the service economy and outsourcing of manufacturing to low income countries. The 2008 crisis didn't manage to quite force a change, although it did cause central banks to step into the limelight. Central bank leaders used to be nameless bureaucrats, but not anymore. Compared to the 60s, in the US blue collar families need both parents working and if they own their home, they probably have more debt that savings. Maybe even if they don't own their home.
The economist doing the presentation argued back then that climate change might be the crisis that forces another shift. There is also the war in Ukraine. If he was right, we are likely to have some fundamental changes in the 2020s economy, perhaps the end of the globalisation trend and/or the move back to quality made products that are repaired instead of replaced within a few years.