More than half of Britons think Prime Minister David Cameron failed to provide leadership early enough to control riots that erupted in London and spread to other cities, a survey showed on Friday.The results of the ComRes poll for The Independent newspaper chimed with those of an ICM survey for The Guardian, in which only 30 percent said Cameron responded well to the riots while 44 percent thought the opposite.The ComRes survey also found that only 36 percent have confidence in Cameron's leadership of Britain in general. A different poll by Reuters/Ipsos MORI on July 20 said only 38 percent were happy with the way he was doing his job.Fifty-four percent said Cameron, who did not return from holiday until the riots reached their peak on Monday, had failed to provide leadership early enough.Five...