While eight of the most powerful men on earth will spend the next three days at Gleneagles in talks aimed at ending poverty in Africa and combating climate change, for the second time this week there have been shocking scenes of violence in clashes between anti-capitalist protesters and police.

More than 100 demonstrators have been arrested and 30 police officer injured during running battles in Stirling and just a few miles from Gleneagles in Auchterarder.

It has been a day of upheaval and confusion for the people of Auchterarder. For months locals had been preparing for thousands of demonstrators descending on the picturesque Perthshire town. But a controversial march planned to follow a route past the gates here at the Gleneagles Hotel was on then it off then it was on again.

Anarchist groups have been promising for months to disrupt the G8 summit. Their tactic was peaceful blockades of the routes to the hotel. There is no doubt they succeeded in causing chaos across much of the road network. One group sat down on the A9 but were quickly moved off the road by the police and surrounded. Some dressed as clowns use humour rather than violence to get their point across.

Chief Inspector David Metcalf from Northumbria Police said: "Their sole aim, from what I can tell from the conversations I had with them, was to block and obstruct the main road. They have no threats or any violence towards my officers whatsoever."

Some protesters walked for 20 miles from Stirling to get to Gleneagles. Many were stopped by the police. Thousands more came by coach to join the march organised by G8 Alternatives. But because of the violence in Stirling and the blockades, the police tried to call it off.

Aamer Anwar from G8 Alternatives said: "We have thousands and thousands of people now sitting on buses, peacefully, trying to get to Auchterarder to march to Gleneagles within 500 metres of the G8 summit. We're now being told by the police that they're cancelling the march. That's not acceptable; we cannot be dictated to in a democratic society by a chief constable or by George Bush."

Faced with the threat of another march in Edinburgh, they relented. In heavy rain, the march passed through the sleepy streets of Auchterarder.

The organisers first applied for permission for this march more than four months ago. Since then it has been on and off, on and off, right up to the very last minute. They were permitted to go as far as a security fence in the town. Waiting behind it was rank after rank of police. Trouble flared briefly, but the real problems began when protesters flooded across the fields nearby.

The government said it chose Gleneagles as the venue for this summit because of its relatively secluded location. That of course means it is surrounded by fields which the protesters crossed those fields to get to the fence. After a stand-off, riot police were flown in, and there were violent clashes, as they tried to clear the fields.

With violence in Edinburgh, Stirling, and now at Gleneagles, the hope that this summit would pass peacefully now lies forlorn and forgotten.