I realise that any sane individual does not advocate genocide as a way of reducing house prices ( strokes chin whilst in deep thought ) but we really do need to either give up on some greenfield areas or stop moaning about the cost of housing. Stark choice.
So what about our current needs? You know, all those people who cannot afford to buy a home, or struggling to find a rental property within their means, or still living with parents even though they are are about 30 years of age? What about now or the next ten years? Get used to it folks...
We need to build millions of homes, there are not enough brownfield sites to fulfill the needs of the population, there will need to be new homes on what is currently undeveloped land. Alternatively we can watch house prices and rents continue to rise. Take your pick?