What's the bottleneck? Obviously the demand is there, right? What's constraining the private supply side to expand? (More explicitly: what happened when the pub

What's the bottleneck? Obviously the demand is there, right? What's constraining the private supply side to expand? (More explicitly: what happened when the public sector building shrunk, why private sector did not pick up the slack?) Is the difference that council housing is in a large part publicly funded? Difference in the permitting process?