Bob Geldof used to be a Boomtown Rat. Now he's just a... Now he's just Bob Geldof.

But he looms like a giant in the public's awareness and bestrides our TV screens like a colossus. I saw him last Saturday afternoon, for instance, at Glastonbury, before the hordes of sentimental spaced-out drones listening to their adolescent drivel - sorry, I mean the boys and girls of all ages and social backgrounds having a good time while enjoying some of the best music in the world.

Worse, not only did I see the great Bob, but I heard him too. He dropped in from a helicopter and yelled at them to hold hands and shout, "Make poverty history". He asked them to repeat the slogan - "louder" - so that he reminded me of the compere of the Christmas pantomime long ago at the Sunderland Empire. But it was the other thing he said that made my flesh creep. He said, "Hold hands, but not as if you're at some hippy rock concert..."

What did he think they were at, for heaven's sake - at Bayreuth for Wagner's Ring operas, or at the theatre in Athens for the Theban plays? Such a combination of screaming mawkishness and crass ignorance would be hard to beat. Geldof's relentless campaign of self-publicity and self-righteousness is just that; and it will do nothing to help the poor. All the billions thrown Africa's way has gone into posh cars, palaces and jumbo jets for its corrupt leaders - and shopping trips for their wives and girlfriends. Or else it has ended up in the pockets of spivs and crooks in the West.

But there's worse to come. Next week the summit of the G8 world leaders will meet in Edinburgh and Geldof has called for a million of his rabble-rousers to turn up for it. There will be trouble. It would be no surprise if there were serious injuries and widespread damage at the hands of these thugs. I saw it happen here in the City of London in 1999 when a trail of desolation was left through the Square Mile by these yobbos who disguise their inarticulate rage and envy under a pretended humanitarian concern. If they really cared about humanity, they would take the trouble to learn something about politics and economics; and they would not rampage through our cities causing havoc.

The temperament in Britain today is a lethal mixture of ignorance, aggression and sentimentality. Any minute it is as likely to break out into rage and violence as into one of its maudlin choruses that pretend poverty and wars can be abolished if only the statesmen had the same moral fibre as Bob Geldof and the protestors with their whistles and painted faces. What moral fibre?

"Make poverty history" - they don't know any history. The problems the world faces will not be solved by marches, pop music, slogans and self-indulgence. Our problems just might be alleviated by intelligence, experience and hard thinking. But TS Eliot predicted the rot as long ago as the 1930s: "We have bodies of men and women of all classes detached from tradition, alienated from religion and susceptible to mass suggestion: in other words, a mob. And a mob will be no less a mob even if it is well-fed, well-clothed and well-housed."

* Peter Mullen is Rector of St Michael's, Cornhill, in the City of London, and Chaplain to the Stock Exchange.