"Anyway, so James, how about it? Ireland has enjoyed housebuilding on something like the scale that you've argued is needed in Britian. Why are prices continuing to rise here? As I said before, genuine question."
I have to say, I don't understand the Irish housing market, so I am in no position to make any comparisons.
Nor for that matter is it the low levels of housebuilding alone that account for the price rises in the UK. If credit were not cheap, then UK house prices would not be rising.
But apart from that, UK housebuilding is at an historic low, and given that credit is cheap, that manifests itself in rising prices, as well as overcrowding and some signs of rising homelessness. If credit were not cheap then the housing shortage would not lead to rising prices, but it would still be a housing shortage, presumably with more people on the streets.