I found this particularly illuminating:

I think a lot of the criminal justice legislation of recent years has been a response to popular newspaper complaints. It’s not wholly new, and the popular press have always tended to be—– made a great virtue of ever toughter policies on law and order, and I don’t know a politician who isn’t in favour of tough policies on law and order, but there has been a wave of ever more noisy campaigns, either following high profile criminal cases or whatever, demanding ever tougher sentences from an ever wider range of crimes, to which government and Parliament seems to me to have most readily conceded.

Part of what I asked myself when I got back in charge of prisons again, after an interval of 20 years: why do we now have double the prison population? Why are all the sentences longer than they used to be when I was led to believe as a member of the public that crime had actually fallen in the intervening time? Some would say it’s cause and effect, but it plainly is not because the longer sentences are for one type of crime and the fall in crime has been in other types of crime, mainly crime against property which sentences … fall, but not much. The answer is really a series of tabloid newspaper campaigns responded to eagerly by government and Paliament and a series of criminal justice bills.

Actually, it’s quite a lot of my officials and people in the criminal justice system, not just me as a politician, that even the courts respond to this strident demand all the time for ever longer sentencers, ever tougher penalties, and you can see the judiciary and the magistrates, if you like, responding to the criticism they would otherwise come under in individual cases if they don’t keep imposing strict penalties.

Obviously as a polician I disapprove of that. I’m not sure it really does represent a genuine public feeling. There are some people who think you would somehow get rid of crime if you just made the prisons nastier and the sentences longer, but it’s not the prevailing public view, and the newspaper campaigns are usually based on a very, very partial account of some very shocking high-profile case.

[…]

I won’t go back, I’m dilating on again, but I just think the clamour from particular newspapers for tougher and tougher Criminal Justice Acts has been responded to. I think prison requires tens of thousands of people in, they are serious criminals who should be punished severely and need to be put away to stop them committing more crimes, but I don’t think you should add people who are really an extremely annoying nuisance and people who really you can get them to stop being criminals if you dealth with them in some other way. Because the prisons are so overcrowded and so difficult to do anything there, we are steadily toughening up an underclass of criminals who keep going round and round in the cycle, in and out, and I blame the newspapers for that.

(Emphasis mine.)