I'm not certain, but I seem to remember that the ballooning of house prices is London-led. What's happened in the past, anyway, is that foreigners have bought homes in London, paying well above the odds, and that has led to a lot of folk becoming very cash-rich, very quickly, which in turn has sparked a ripple effect, as they buy houses for their relatives or in different pars of the country and so on. There are several examples that I know about here in Llandudno.
The most common event has been those in the public services- teachers, nurses, doctors, etc., who've had modest semis in London, sold up and bought small mansions here. That sort of thing simply fuels the price rises, and has the ridiculous knock-on effects that we're seeing, where our own young folk can't possibly afford to buy.