One of the previous charts that I have uploaded to this thread highlighted the link between mortgage approvals and the yr-on-yr change in house prices (post no. 620).
Looking at this chart again I noticed that the rate of decline in yr-on-yr growth for the four periods that we have seen since 2000 (including the one that we're experiencing now) were similar. Plotting these highs and lows in year-on-year growth confirmed this view and suggested that by June 2011 the average price might be 10% lower than that of June 2010.
Below is the chart from post 620 followed by the comparision of declining growth periods: