UK Stocks-Factors to watch on May 4

May 4 (Reuters) - Britain's FTSE 100 index is seen opening 16 points higher on Thursday, according to financial bookmakers. * BHP: Australia warned on Thursday that a push by activist investor Elliott Management to ditch global miner BHP Billiton's dual listing may be a criminal offence and could be subject to civil penalties. * ROYAL BANK: Investor advisory firm Institutional Shareholder Services has advised shareholders in Royal Bank of Scotland to vote against its remunerati