Indeed, and that has long been the case. For a very very long time, people have been talking about unaffordability for ordinary workers leading to a price crash

Indeed, and that has long been the case. For a very very long time, people have been talking about unaffordability for ordinary workers leading to a price crash - but this has never happened due to insatiable demand coupled with low interest rates. Of course London is expensive but equivalent accommodation in places like Paris, New York, SF, and Singapore isn't that far south per sq meter, especially as a percentage of salaries. Unaffordability is also a red herring - when prices became unaffordable in Japan, lenders just introduced longer multi-generational mortgages. While that is obviously distasteful, it illustrates that demand is sufficient for even those kind of deals to get taken up. This isn't to defend political inaction on the issue, but many people protesting don't seem to have a sufficient grasp of the fundamentals to make cogent proposals that could improve the situation. I believe the foreign investment market is already slowing but if you wanted to make a dent in it, you could introduce duties or prohibitions on foreign owners and/or vacancy.