May Day mayhem

The morning gathering in Hyde Park was peaceful

The BBC's Adam Brimelow at the May Day protests.

It all began as a celebration. The idea was to gather outside Parliament, take over the streets, and reclaim the area for nature.

They called it "guerrilla gardening" - demonstrators brought trowels and spades to dig up the grass and plant saplings, shrubs and vegetables.

There was a carnival atmosphere

They sat in the sun, smoked, chatted, played music, and contemplated a better world.

One young demonstrator, dressed as a tree, explained to me that "just as every grain of sand makes up a beach, every person here makes a difference".

I asked him what the difference would be. He said it would encourage people to think for themselves, rather than being told what to do.

Spirit of fun

There was not much focus to the protests, but no one seemed to mind. Some people were concerned about domestic issues, others carried placards condemning the world bank.

Some were worried about human rights abuses, others about the international arms trade.

The overriding theme was anti-capitalist but the emphasis was on peaceful protest, in a spirit of fun.

Later on, violence broke out

But the party atmosphere began to change. Statues of famous figures around the square, including the former prime minister, Sir Winston Churchill, were daubed with graffiti.

Some people in the crowd became restless and headed off towards Trafalgar Square.

On the way protesters smashed a McDonald's burger restaurant. A police officer was hit by a brick and several people were arrested.

Officers who had been waiting nearby moved out of their vans, unwrapped their riot gear, and formed a tight cordon behind their round plastic shields, redirecting some people, blocking others.

Tony Blair has condemned the vandalism

The crowd became more militant, the police became more forceful.

This was the biggest police operation of its kind in London for 30 years. The overall strategy was cautious, with relatively few arrests.

But the disorder right at the heart of London will raise renewed questions over handling of the protest.