It’s a really weird take you see on occasion. Like, over a third of households in England own their house (or flat) outright, and millions of people are on very generous final salary pensions (closed to new entries of course).
The amount of food and housing (by area, housing got smaller) the average person can afford has gone down in that time.
How long did it take to pay back its War Debts?
What would that indicate? The government hadn't paid off the payments from the 1837 Abolition of Slavery Act until 2015, but that was based on the way they structured repayments. To say that from 1837 to 1946 that Britain wasn't a superpower, that would seem a tad absurd to me.