Dan42,
Lots of things contribute to an every increasing push on house prices.
As IP Freely mentions above.
But also, inflation gradually increases the prices and cost run up over time
bigger and bigger houses and extensions all increase average prices cost of land development with government costs.
wages slowly increasing mean more money available
rates have dropped to what 30 year lows at the moment, thus more money can be loaned for same wages
more and more people are buying as tenants in common so they can afford more expensive houses.
Basically, everything is in favour at the moment of large house price increases, BUT, house prices are basically flat and negetive over the last 4 years taking inflation into account.
So what is going to happen over the next year or so with unemployment starting to bite, probablility of rate increases, nil or very little wage increases, debt biting into most peoples incomes, etc. Government going broke thus will need to increase rates on everything, power costs surging, water prices surging, council rates surging, food prices surging, etc
Thus I would expect some small price rises now and then , but prices to fall over the next year or two.