>There was a slight slump in rentals after the financial crisis, not before

And a significant decline in mortgages over that time, likely due to mortgage law changes as a result of the crash. Making it slightly harder to get a mortgage would, over time, move people from mortgages to rentals, which is exactly what the data shows, right?

UK added Basel capital rules, the affordability test, and changed capital ceilings in banks, among other changes. Academic papers list these as being major drives in declines in UK mortgage rates. Those people rent instead.

All with no need for speculators to drive the market up - the laws changed.

>Social rentals, which you are bizarrely conflating with private rentals

Ah, so now we're only taking a subset of renters. Good idea.