sale@ (Removes extraneous word in para 11) * CFO Stevenson to take up opportunity elsewhere * RBS holds AGM in Edinburgh * Speculation government set to sell some of its stake * Branch closures spark protests outside RBS sites EDINBURGH, May 30 (Reuters) - Royal Bank of Scotland's finance chief quit unexpectedly on Wednesday and cast doubt on the timing of a possible sale of some of the British government's controlling stake. Former investment banker Ewen Stevenson declined to say where he was going or exactly when at the bank's AGM. "You'll know when there is news to tell," he told reporters at RBS' headquarters in Edinburgh, where the meeting was held, while RBS said a leaving date would be confirmed in due course. Asked about reports the government could start selling down its more than 70 percent RBS stake this week, Stevenson said a sell-off in bank stocks sparked by nervousness over political developments in Italy and Spain made this unlikely.