The Conservatives took action several times - generally by changing the rules around Mortgage Insurance and downpayments, and We just had another similar change in December.  The effect was that prices still went up and those with low income just found it harder to buy.

Unless they are 1. going to restrict ownership to residents, and 2. fiddle with the Capital Gains rules I can see where anything will make a difference.  

As long as there is more money than supply there are going to be increases in the major cities.  The only thing I can see really stopping the foreign money is a residency requirement and perhaps that they be bought with out a loan but then there are still wealthy people that could get around those rules