House prices are manipulated by governments who feel that they need to be seen to 'do something'.
Negative equity is a function of overlending and the British obsession with 'making money' on your house purchase, it barely matters if you are not looking to sell. That said, the inability to clear your mortgage when selling will put breaks on the market so even if you are trying to cut costs by downsizing, you will find that very difficult.
The biggest problem remains the disconnect between supply and demand, way too much demand pushes prices up which in turn pushes up private sector rents. This of course suits the banks and mortgage lenders and the government is happy as it keeps a big slice of the population hard at work.