Which one of these men would you vote for?

On the left, David Blunkett, Labour Home Secretary. On the right, Oliver Letwin, his Tory shadow. Bu

About this time last year, Harry Fletcher, a spokesman for the National Association of Probation Officers, received a call from a politely spoken man, asking if he would be good enough to meet Oliver Letwin, the shadow home secretary. Fletcher was taken aback. He had forgotten what it was like to be courted by politicians. Since Tony Blair seized on the murder of James Bulger when he was Labour's shadow home secretary in 1993 and began the competition between the parties to discover which might most shamelessly turn popular fears of crime to electoral advantage, Fletcher had been an often lonely opposing voice from outside the bounds of polite political society.

Examine the thousands of cuttings on the criminal justice system in the years since, and you will see why. There will be hundreds of Fletcher-inspired attacks on gesture politicians. When the Conservatives tested the electronic tagging of offenders in a pilot project in the north-east, they presented it as the first step towards a hyper-efficient, Robocop future. Fletcher checked the reality of techno-crime fighting with his members. One Geordie had ripped his tag off and fled to Brighton, they told him. (He gave himself up because he couldn't stand living with southerners.) A second kept waking up to the sound of security guards bursting into his house. He had done nothing wrong. It was just that when he rolled into a blind spot under his duvet, the alarm shrieked in the monitoring station. Virtually every new Labour initiative - from curfews to anti-social behaviour orders - has been punctured with similar aplomb. Fletcher is a kind of clearing house for the contemptuous and exhausted in the law and order bureaucracy; the men and women who have to cope with the consequences of a political hysteria that sees a new crime bill hitting parliament annually. As he is a far more informative and trustworthy source than the Home Office, his phone is clogged with pleading calls from correspondents gagging for leads and leaks.

The regime loathes him. Jack Straw denounced Fletcher as "a relic of the Seventies" - the worst insult in the new Labour lexicon, implying a belief that you can't reduce crime without reducing poverty. David Blunkett refuses to meet him or his union.

"Could you come round Thursday morning?" continued the nice young Tory, who apparently knew none of the above.

"Well, what time on Thursday morning?"

"Oh, all of Thursday morning."

Fletcher accepted and wondered how he might make conversation "with a load of Tories for three hours". As it was, the time shot by and everyone got on famously.

If it is possible to be further beyond the pale than Fletcher, then Frances Crook, director of the Howard League for Penal Reform, is out there. The consequence of the competition that Blair began was a rise in the prison population from 42,000 to 72,000 (and it's still going up). Crook believes that prison is the worst place to put all but the most dangerous offenders; in part for their sake, in part because they will come out as hardened cons and commit worse crimes. Once a faintly Labourish sympathiser, she now sees Blair as the propagator of "the big lie that capricious, erratic and relentless imprisonment helps the victims of crime". His monument is a "contagious culture in which revenge and punishment are the only appropriate responses to antisocial behaviour: the culture of a lynch mob".

Blunkett won't talk to her, either. Letwin did. She found him open and intelligent. Feeling faintly embarrassed, she accepted his invitation to a Conservative women's conference. Iain Duncan Smith and the other speakers from the platform talked about the need to care for the vulnerable. "What if the vulnerable are also antisocial and criminal?" she asked. They must be cared for, too, came the reply. Crook left not quite believing what she had heard.

While the Conservatives were looking for ideas from unlikely sources, Blunkett was lowering the moral standing of the Home Office even further. You might have thought, for instance, that the disappearance of the Soham schoolgirls would have prompted decent restraint - at least until detectives knew if the children were dead and who had killed them. When desperate officers said one Friday that they had a vague suspicion that the girls may unwittingly have contacted a paedophile in an internet chat room, the Home Office swooped like a carrion crow. It briefed hacks that Blunkett was preparing to clamp down on internet chat rooms. By the time the papers carrying this news were being read on Saturday morning, the police had checked the girls' computers and found nothing. If Ulrika Jonsson sells the story of a TV presenter forcing himself on her, Blunkett briefs how he's going to tighten the law on date rape. If the tabloids incite hatred against asylum-seekers, Blunkett cross-dresses and warns, in true Thatcher style, of schools being "swamped" by swarthy-skinned aliens. If the papers denounce civil libertarians, Blunkett joins in and rails against "bleeding-heart liberals" supporting Asian "maniacs" who are "whining" about the length of their sentences. Blunkett has no line in the sand. There's nothing he won't do.

I hope I don't appear to be attacking Blunkett personally. He is simply an embodiment of the spirit of new Labour - any other Labour home secretary would be the same. In his justifiably famous leaked memo of 2000, Blair told it like it was when he ordered his cringing officials to find "two or three eye-catching initiatives". It didn't matter what they were as long as they were "tough, with immediate bite". Blair let the truth slip when he bellowed to William Hague and Ann Widdecombe, the then shadow home secretary, in 1999: "What is the alternative? What does the Right Honourable gentleman offer? Why was it that he made a policy-free speech, apart from a load of nonsense from the shadow home secretary, most of which we are doing in any event?"

To their great credit, the Liberal Democrats never played the nonsensical game, even though conventional wisdom held that it was essential for them to pose as hard men if they were to hold on to their gains in Tory England. Now the Tories are picking up their ball and walking away. In his speech to this year's Conservative Party conference, Letwin didn't flutter eye-catching initiatives in front of the delegates but concentrated on dull measures that would reduce crime rather than exploit the fear of it. He promised he would increase treatment programmes for drug addicts tenfold, and get children out of Feltham Young Offender Institution and similarly murderous hell-holes, and into small training centres where they might just learn to read and write.

His present theme is that the government threatens the basics of English liberty. In recent months, ministers have come within a stutter of saying that it is as bad for the guilty to go free as for the innocent to be convicted. Translated into law, this means that a defendant should no longer be presumed innocent until found guilty beyond reasonable doubt by a jury of his peers, but presumed innocent until found guilty on the balance of probabilities (and probably not by a jury of his peers, given new Labour's aversion to the democracy of the courtroom). The prejudicing of trials by other means is probably on the way. If Blunkett allows prosecutors to reveal the previous convictions of defendants indiscriminately, the innocent will be jailed - and, by extension, the guilty will go free. Letwin is against Blunkett on that, too.

In government, Blair and Straw have broken just about every promise they made in opposition. Those of us who objected were given a sharp lecture on political realities. Shut up and get in line, we were told. Unless Labour hypes up crime, the Tories will seize it as an issue and get a step on the ladder back to power. Letwin's arrival removes that excuse. The government isn't doing what it is doing because it has to but because it wants to. Its flight to the right has abandoned the centre ground as well as the left-of-centre ground in home affairs to the Tories and Liberal Democrats.

In conversation, Letwin is as open, intelligent and serious as Fletcher and Crook said. He is also respectable, and you can never underestimate the importance of respectability in Britain. Most on the right are obsessed with sex and believe that permissiveness destroyed respectability. They don't understand that a modern respectability flourishes, or, if they do, they dismiss it as political correctness. None the less, it is not respectable to rant about the queers and blacks. Even if parts of the audience half-agree with you, most do not believe it is proper for public figures to go on so. Hague learnt this to his cost at the last election, when he stood on a platform constructed of Daily Mail editorials and crime and race cards, and lost decisively. Modern respectability also places great emphasis on sincerity and individualism, which new Labour's manipulative and dragooned politics offends. Much of modern respectability is hypocritical, but so was much of the old respectability. It doesn't mean that it doesn't matter.

Compared with Blunkett, Letwin is respectable. If you think I'm blathering, try this test. I guess, perhaps presumptuously, that most New Statesman readers wouldn't call themselves Tory. So mentally strip off their party labels and let Blunkett and Letwin face each other mano a mano. Who would you vote for and why?

Mary Riddell interviews Martin Narey, head of the Prison Service, page 30