The quality of the house your grandparents (for 1920 probably your grand-gran parents) is vastly different. Those houses cannot be compared at all, when I take my dump in the heated warmth in a nicely smelling place listening to some music over my airpods.
That house trades at 13x now.
There is no house of any size for 3x in most areas of the UK.
You can’t handwave that away by saying “central heating”. The cost of part-of-a-house is far less than the total - not 10x more on top.
Part of the issue is population doubled since then but house building didn’t. Part is cheap debt in the 2000s turned everyone and their dog into buy-to-let landlords then AirBnB hosts.
Let's look at some real numbers instead of a folksy parable about grandma. Here are recent stats about rent arrears:
https://www.baselane.com/resources/unpaid-rent-debt-statisti...
And rental affordability:
In 2026, a full-time worker needs to earn $34.73 per hour to afford a modest two-bedroom rental home in the U.S. and $29.19 to afford a modest one-bedroom rental.
And mortgage affordability:
https://www.visualcapitalist.com/median-house-prices-vs-inco...
None of these are heading in the right direction.