Between 1996 and 2006 the British police spent over 500 million pounds (don't know what that is in A$ but it's about a billion Canadian dollars) installing 4 million surveillance cameras in the country, including over 1 million in London alone. How many will there be after 2012?

Last summer the London Metropolitan Police published a study in which they admitted that less than one crime per year was solved per 1,000 cameras in London. Note that's "solved" after the fact, not prevented - the crime rate in London apparently hasn't changed very much.