With a sustained negative fertility rate over the past few decades, there could've feasibly been stable prices with no new houses built at all.
Obviously the property market would be looking very differently if population was decreasing. The whole economy would.
Isn't this exactly what's happening in Japan? Govt practically giving away mostly rural homes, as owners died without heirs.
I think it would've been much earlier than that. Cumulative net migration since 2000 is around 8.5 million people. So the UK's current population would be radically lower today without immigration.
https://www.statista.com/statistics/283287/net-migration-fig... (annoyingly the per year figures need to be summed up manually on both this and ONS reports)
ONS data states that the average house price outside of London and the South East rose from £134k in 2005 to £192k in 2019 [0].
The Bank of England's inflation calculator states that £192k in 2019 costs £139k in 2005 [1].
Looking at London specifically, house prices more than doubled from £303k to £684k over the same period [2]. That's a 63% increase in real terms. Immigration would have some effect on this, but so would UK citizens moving to London or foreign nationals buying up property as an investment.
[0] https://www.ons.gov.uk/economy/inflationandpriceindices/adho...
[1] https://www.bankofengland.co.uk/monetary-policy/inflation/in...
[2] https://www.home.co.uk/guides/house_prices_report.htm?locati...
Of course not all UK citizens are white British, and the negative fertility rate would've applied downward pressure, and it's conceivable that white Londoners emigrated to Australia etc at a higher rate than other parts of the UK. But none of these factors can really explain a 50% decline in population in the same way that internal migration can. It certainly becomes very difficult to reconcile the numbers if any signifiant number of people from predominantly white areas had been moving into London.
I agree with you that most of the change in average UK house prices is driven by London. In a zero immigration scenario it seems likely that London prices would be radically lower with the rest of the country having much less, if any, change.
