i remember reading somewhere that it was possible to take a short
> position by using spread betting techniques.
> can anyone give more info ?
You could buy a spread bet on the house price index which will pay money out if the index falls. However, if the index rises, you will have to pay the spread betting company money. It's not like putting money on a horse where the worst that can happen is that you never see it again.
There is the option to put a "stop gap" to limit your potential losses. However, if the house price index were to rise to above that point, then crash afterwards, you would not benefit from the fall.