By Agence France-Presse, Updated: 8/28/2011

London's Caribbean-flavoured Notting Hill Carnival got under way Sunday amid hopes that Europe's biggest street festival would not be marred by a repeat of this month's devastating riots.

The two-day extravaganza in west London attracts up to a million revellers to watch troupes of dancers in exotic costumes perform on floats as powerful sound systems pump out music.

But the festivities almost did not take place at all following England's worst riots for decades and Scotland Yard is deploying 5,500 officers on Sunday and 6,500 on Monday, about a thousand more than last year.

The urban unrest, which started in north London on August 6 before spreading across the capital and to other cities, caused enormous damage and left five people dead.

Add to this the Notting Hill Carnival's reputation as a magnet for troublemakers, and many questioned whether the event should go ahead.

However, organisers were not ready to admit defeat, especially because the carnival itself originated as an act of defiant celebration in response to race riots in the 1950s.

As the parades got underway, festival-goers expressed their delight that the carnival went ahead.

"It's a chance to show we can do other things and have a good time," social worker Graham Randall told AFP.

"It's healing for the riots. It shows everybody who comes here that we can have a good time in the streets."

Revellers milled between the stalls and thumping sound systems, drinking, dancing, and tasting jerk chicken as the smells of open-cooked Carribbean food wafted through the air.

 In the thin sunshine, youngsters dressed up as dragons paraded through the Notting Hill neighbourhood on what is traditionally "children's day" at the carnival.

"This year, carnival is very significant for us in light of the recent events in London," said Ansan Wong, a funding director for one of the bands taking part.

"We are hoping that this theatre on the streets will engage several people from all communities to bring the celebrations of the diverse cultures of London."

The carnival was founded in 1964 following the disturbances in Notting Hill six years earlier which saw clashes between whites and newly arrived immigrants from the West Indies.

Ancil Barclay, the festival's co-director, said cancelling the event would have been the wrong response to the frenzy of rioting, arson and looting earlier this month.

"We are not going to let a minority stop us from doing what we want," he told AFP.

"Cancelling the event would have had a negative impact and would have sent a bad message with the Olympics next year."

London Mayor Boris Johnson said the carnival would "let the true spirit of London shine through".

The event will finish three hours earlier than normal to allow crowds to disperse before darkness falls.

Nevertheless, several shops have boarded up their fronts as a precaution and the authorities are primed.

Scotland Yard told AFP it had made 40 arrests ahead of this year's event, targeting known thugs planning to exploit the festival for violence and criminal activity.

"We do have intelligence that some gangs do want to come to the carnival and create trouble for us," Commander Steve Rodhouse said.

This year's event was taking place in "unusual and exceptional circumstances", he added.