Paul Vallely: My advice to Blunkett is to put a sock in it, motormouth

Mr Blunkett would robustly riposte that this was just plain speaking in keeping with his bluff instincts

You can always get a cheap laugh by having a go at Liz Hurley. Throw in a disparaging reference to an ageing actress like Joan Collins and you can more than double the chortling. What larks the Home Secretary, David Blunkett, had the other day talking to business leaders in his home city of Sheffield. And that was not all.

In addition to taking a sly side-swipe at the two starlets – and their recently publicised fears that London is now more dangerous than New York – he took the opportunity to launch withering attacks on a whole raft of the kind of people whom small-town shopkeepers love to hate.

There were the Asian rioters in Bradford he called "maniacs" who "burnt down their own businesses" and were now "whining about sentences they have been given". Then there were the "bleeding-heart liberals" who had sympathised with those Muslim community leaders who had persuaded rioting youths to give themselves up to the police – only to find they were given prison sentences as long as five years for stone-throwing. And finally he directed a blistering broadside at the media. "The more you get crimes reported," the poujadist politician lamented, "the more reported crime goes up, the more I get slagged off by the all-knowing, less-understanding national press."

Even by David Blunkett's motormouth standards this was a startling diatribe. Had he upped the slang quotient more he would be well on the way to become the George Bush of British politics.

The Home Secretary would no doubt robustly riposte that this was nothing but plain speaking in keeping with his bluff, working-class, "Sheffield lad" instincts. Or he might argue that directness was the only way to reclaim some of territory the left has lost to political correctness. But the truth is there was something altogether more unpleasant about it.

Certainly directness has characterised his mode of discourse in the past. As Education Secretary he was more blunt with the teachers than any of his predecessors, including Margaret Thatcher. Early on in his present job he was so rude to the police over pay that he provoked talk of a strike, for the first time since 1979, until he retreated with a humiliating apology.

But since those days his language has got out of hand. All too often outlandish insults seem to be substitutes for quality of argument: those who objected to the draconian nature of the anti-terrorist legislation he tried to introduce immediately after 11 September were denounced as "airy-fairy" libertarians.

Then there were the asylum-seekers. Doctors' surgeries, he announced earlier this year, were "swamped" by them. The last time that word had been used by a major politician in connection with immigration was when Margaret Thatcher had employed it to describe the feelings of British voters towards "people with a different culture". Blunkett was unrepentant. The next day he went on the Today programme and said – disingenuously, in the light of the racist overtones of the Thatcher usage – that he had looked it up in the dictionary and it seemed perfectly apt. They were swamping schools too, he added mischievously.

It is not policy which is at question here (there was much that was sensible in his Asylum Bill). It is language. And pretty much the same thing could be said of his white paper on immigration, which contained some good ideas but which he launched with a gratuitous headline-grabbing attack on forced marriages and female circumcision in the Asian community.

Are all these expressions of gut white-van man prejudices? Or crafty political signals designed to convince Middle England that New Labour is on their side? Tony Blair is in little doubt: David Blunkett, he has said, is a "very canny politician".

Which only makes it worse. Blunkett now denies the comment once attributed to him when he was at Education to the effect that, if he were put in charge of the Home Office, he would make Jack Straw look like a liberal. "I have never said that and I do not believe it," he has said. "I am a rational balanced politician." If so, he has a funny way of showing it.

Ideas like the one that TV cameras should be brought in to film people being deported from Britain – to show the public that the asylum system is working – are pretty despicable. They turn human tragedy into a kind of game show. This is not presumably quite what Tony Blair had in mind when he urged his ministers to "think the unthinkable.

Blair himself is quite hard-nosed about all this. He knows that across Europe leftist governments have lost power to right-wing parties espousing populist prejudices. And he himself in Opposition, as shadow to the Home Office brief, managed to find a way, with his 'tough on crime and tough on the causes of crime' strategy, of projecting himself as simultaneously tough and caring. Yet he did so without having recourse to the kind of crude language which Blunkett has embraced and which has made him, it is said, the only Cabinet member with whom the editor of the Daily Mail will lunch.

There is a difference between thinking the unthinkable and saying the unsayable. And David Blunkett should learn that before his bleeding-heart liberal supporters become bleeding cross ones.

p.vallely@independent.co.uk