RIOT police clashed with protesters in central London yesterday, arresting at least 57 people as activists targeted some of the world’s biggest companies ahead of next week’s G8 summit. About 100 protesters gathered outside oil giant BP’s headquarters, while others convened at the office of US defence firm Lockheed Martin. Office workers in Soho were also disrupted. Nearly 1,200 police were mobilised to deal with the protests. Police said they had arrested people for offences including criminal damage, assault on police and possession of an offensive weapon.