Here's a report from the local paper The Argus, followed by some personal comments:

ARGUS REPORT - "Anti-war march 'unlawful'"

Police have accused anti-war marchers of acting unlawfully because they did not inform them about what route they would take.
Dozens of officers formed a human barrier to stop more than 200 protesters marching along North Street in Brighton and entering Churchill Shopping Centre on Saturday afternoon.
They also diverted traffic while some protesters carried out a sit-down demonstration at the roundabout on the seafront next to the Palace Pier.
Officers from all over Sussex were drafted in to help their Brighton and Hove cou terparts control the crowd, which was largely peaceful.
But Superintendent Peter Coll branded the march "unlawful".
He said: "I am saddened the organisers failed to talk to us and co-operate before this event. I feel they do their cause a disservice by acting unlawfully.
"It has always been our intention to facilitate lawful and peaceful protests but closure and disruption of the main South Coast road and a city centre packed with Saturday afternoon shoppers is unacceptable."
Members of Sussex Action for Peace (SAFP) and the public began their protest against war in Iraq by the war memorial in the Old Steine. People waved banners and there was a carnival atmosphere with jugglers and dancers.
They had intended to walk past the Pavilion, up Trafalgar Street, down Church Street and then down Western Road but police wanted them to walk along the seafront.
SAFP member Chris Osmond said: "There were negotiations between some people on the march and the police on the day.
"The police tried to stop us going up Trafalgar Street, which was a bit counter- productive. If they had allowed us to continue our original route, it would have saved them a lot of trouble. I think it was a successful march. People wanted to express themselves and let the residents of Brighton know there is a strong anti-war movement in the city."
Five people were arrested during the afternoon for public order and obstruction offences including one for possession of an offensive weapon.

SOME COMMENTS:
Not a bad report by the Argus' standards.
I think it would be really good if people on the wrote to he Argus complaining about the police's behaviour. Had they let people march the route they wanted there would not have been any hassle. Instead we get a line of cops at the end of Trafalgar Street with their batons raised!
There was another march, back on 23 Nov 2002, this was arranged with the police beforehand, then they would not let people go down Western Road (main shopping street).
What we have is Sussex police acting as a political police force trying to prevent people showing there is resistance to this planned war.