BBC on Police Kettling Tactic

Writer and director Zia Trench thought she might visit the G20 demonstration in the City of London earlier this month.
"I wasn't sure if I wanted to protest, but I thought I'd check out the demonstration, and show my face for half an hour," she said.
"As I walked out of Cannon Street Tube I literally found myself facing a line of police. When I asked if I could get through, the police refused. They then moved me down the street towards the Bank of England."
There, Ms Trench joined a growing group of protesters corralled within a circle of police in the square in front of the Bank.
Held by the police within the circle for up to seven hours, the protesters found themselves trapped.

BBC on Police Kettling Tactic - is this how we want our Police to behave?