More than 500 police deployed, Met sayspublished at 13:25 BST
The Metropolitan Police says today's parade is one of its largest policing operations of the year.
More than 500 officers will be deployed alongside specialist search and drone teams, it says.
A dispersal zone is in place, meaning officers have the power to ask people to leave the area for 48 hours. The Met says this is to prevent anti-social behaviour.
"We want everyone attending to enjoy the day safely," Commander Stuart Bell, the officer leading the public order operation, says.
"We expect the vast majority of those attending on Sunday to do so safely and responsibly. However, anti-social behaviour, violence or any other type of criminality will not be tolerated. Officers will take action against anyone attempting to cause disruption or harm."
























