A 12 year-old boy (R) shields his face as he leaves Manchester magistrates' court with his mother after admitting burglary, during the recent riots in Manchester, northern England August 11, 2011. Prime Minister David Cameron, facing a defining crisis of his premiership, promised on Thursday to crack down on street gangs as a national priority and said rioters behind Britain's worst violence in decades would be hunted and punished. REUTERS/Nigel Roddis (BRITAIN - Tags: CIVIL UNREST SOCIETY POLITICS CRIME LAW)