Domimic Lawson has a superb piece today on prisons:

Between 1993 and 2001 - New Labour adopted the Michael Howard approach - the average number of people in prison rose by about 45 per cent. It is notoriously difficult to know which crime figures to believe, but the British Crime Survey, which the current government regards as the most reliable, shows that between 1995 and 2001 recorded crimes fell from more than 19 million to 12.6 million.

Even if you are of the view that prison has no deterrent effect, you still can not dismiss this correlation as a coincidence. The Home Office report, Making Punishments Work, estimates that the average offender carries out 140 offences a year: the figure for those with an admitted drug problem is 257 offences per year. You do the math: it's clear that a large slice of the dramatic drop in crime - and commensurate reduction in the misery of victims - recorded in the British Crime Survey was down to the "incapacitation" effect of prison.

...I can understand why many commentators are distressed that we imprison a greater proportion of the population than any other European country save Luxembourg; it does not speak well of us as a nation. The less-quoted statistic, however, is the prison population as a proportion of crimes committed. That paints a more pertinent picture. In England and Wales 12 people are imprisoned for every 1,000 crimes committed. In Spain the figure is 48 per 1,000; in Ireland it is 33 per 1,000. Both those countries have much lower crime rates than ours.

I am always banging on about this latter statistic, and how it is the only one which counts. If you can hang on until 2008, you can read even more about it (and many other things, too) in my new book.