Really? That's it? Just access to credit?
There's no shortage of labour?
There's no issue with land suppy?
The fact that the sector is grossly inefficient isn't a problem?
If the developers had better access to credit the builders would just appear, the land would become available and prices would drop. Is that what you are saying?
Off the top of my head I'd say it has to do with Capital Ratios, the large number of Tracker Mortgages which are even less attractive in a low interest environment, the unwillingness of the courts to allow repossessions and the high costs they face in what is a small market.