More financial institutions than previously disclosed may be at risk of attack and an Al Qaeda operative has told British intelligence that the groups target date is early September, intelligence sources said yesterday.The operative, described as credible by British intelligence, told his debriefers that the attack would take place '60 days before the US presidential election' on November 2, according to a former National Security Council official.On September 2 President Bush is expected to address the Republican National Convention at Madison Square Garden. Counter terrorism officials are analyzing data from a computer siezed in Pakistan last month to see if...