According to Scotland Yard estimates, 110,000 people participated in the demonstration, while Robinson himself said that millions took to the streets.

Reports from the demonstration in central London show streams of people stretching for many blocks.

The"Stand Up To Racism" counter-demonstration has gathered 5,000.

A police spokesman said it was difficult to estimate the number of participants. Surveillance cameras and footage from a police helicopter were being used for this purpose.

Law enforcement officials acknowledged that the estimates of the police and organizers may differ.

1,600 police officers are involved in maintaining order.

Robinson has billed Saturday's march as a demonstration for freedom of speech and said the event is a defense of British heritage and culture.

The march comes as a debate rages in Britain over policies to combat illegal immigration, as hundreds of illegal immigrants continue to arrive in the country across the Channel.

This summer, there have been numerous protests outside hotels housing illegal immigrants. Some of them have been violent, and several people have been arrested.

Saturday's march featured many British and English flags, with participants chanting"We want our country back."