"We'll see what happens. For the time being rents are rising but properties are being reallocated from investors to owner occupiers at a lower price than would be the case without the tax, which is a good thing."
A good thing for the would-be owner occupiers, perhaps, but not relevant to the question of alleviating the shortage of residential property.
And we don't have to see what happens: policy failure that has failed to shift the supply curve to the right is already writ large.
Insofar as it relates to alleviating shortage of housing, it can't be said the raising of tax is a good thing to the required end of right-shifting the supply function.
At best, it is a neutral thing.
At worst, it acts as a deterrent against the formation of new housing stock.
