One man who will be glad to see the back of this week's Republican convention in Philadelphia is the city's police chief, John F. Timoney.

Charged with controlling the tens of thousands of demonstrators, anarchists and "direct action" vigilantes who converged on the city for the convention, he spent the week cycling back and forth from the front line of protest like a beleaguered war general, trying to negotiate truce after fragile truce.

And, on occasions, the outspoken police chief, clad in police-issue shorts and golf shirt, got stuck right in the thick of things. He described how during one "knockdown, drag-out brawl" he was pushed off his bike - the vehicle of choice for the city's 7,000 police officers - and struck over the head with it.

"It ain't cricket," Commissioner Timoney said, summing up the behaviour of the protesters.

Somewhat less diplomatic language was attributed to him during the week. The Washington Post had reported him declaring in the middle of one melee: "all bets are off . . . you're a bunch of thugs and vandals."

Regardless of what America's police chiefs think of them, however, the self-styled direct-action protesters - 269 of whom were arrested during the week - are here to stay. Many of those on the streets of Philadelphia were at the mass demonstrations against the World Bank in Seattle and Washington last April.

And their numbers have since swelled, with up to 20,000 at the Republican convention, according to official estimates, many organised under banners such as the Ruckus Society, New York City Direct Action Network and R2D2K, a reference to the two political party congresses this year.

The protests covered a range of issues from US involvement in the Colombian drug war and its support for Iraqi sanctions responsible for the deaths of thousands of children to the expense of AIDS medication and the use of the death penalty, particularly in Governor George Bush's home state of Texas.

A common theme, however, was the power of US multinational corporations, blamed for running Third World sweatshops and providing the impetus for the government's harsh economic policies.

One of the bigger events during the week was a parade of "the goats with the votes". Some 400 demonstrators wearing goat masks blocked off street junctions to complain about America's two-party electoral system "run by just one party - the corporations".

The motivation behind some of the protests, however, was a little more difficult to understand. One group of demonstrators, dressed as clowns and led by an 18-year-old Philadelphia student who went by the name Snogg, held a protest about protest. "Us clowns are protesters at heart," Snogg explained.

With protest leaders insisting on being called by such names as Fuzzy-Wuzzy, PigPen and Possum, it was difficult for the media not to have a bit of fun too. The Washington Post described an abortion-rights demonstration as ending with feminists "rallying outside police headquarters, sustaining themselves with tofu-mushroom soup and sprout salad prepared by an impromptu cadre of radical cooks".

But, despite the inevitable humour, the protesters did succeed in getting their more serious message across to the public. Femi Johnson, a cab driver who had been trapped by the demonstrators, summed up the attitude of many of Philadelphia's citizens when he said he didn't mind the disruption.

It was all about letting people express themselves, he said. "I'm from Nigeria and one day I wish to go back and deliver a lesson in democracy like this."

As for Mr Timoney's efforts, he received high praise from the city's business leaders, Governor Bush and even some of the demonstrators themselves.

What violence there was on a much smaller scale than the clashes in Seattle and Washington. No tear gas was used and there were few reports of innocent bystanders being swept up in police operations.

The more tolerant approach may well prove to be a model for other cities which can expect similar events in the coming months. Already, the demonstrators are turning their attention to the Democratic National Convention in Los Angeles later this month.