On the Halifax index, house prices are now down 21.2% from their peak of August 2007. So, in August 2007 the average house receiving a Halifax mortgage sold for £201,081. The average house in December 2008 sold for £158,437.
And that's the drop before much rise in unemployment, and before much in the way of repossessions or other distressed sales. It's not implausible that 2009 could be worse than 2008.
We renters get richer every day...