<p><br /> The Tory lead over Labour has grown to nine points according to the latest pre-election opinion poll but both main parties saw their vote share drop as the Liberal Democrats gained ground.<br /> </p><p><br /> An ICM survey for The Guardian put David Cameron's opposition on 38 per cent - down one point on that pollster's last results - with Gordon Brown's governing party dropping two points to 29 per cent.<br /> </p><p><br /> The Liberal Democrats - perhaps boosted by the popular showing of economics spokesman Vince Cable in this week's televised debate of would-be chancellors - gained four to stand at 23 per cent.<br /> </p><p><br /> ICM surveyed 1,003 adults across the UK by telephone on March 30 and 31.<br /> </p><p><br /> Meanwhile, the Daily Telegraph said another 14 senior business figures - including former McLaren Formula One team boss Ron Dennis and Simon Fox, the chief executive of HMV Group - had joined the public endorsement of Tory tax plans.<br /> </p><p><br /> David Cameron and George Osborne have promised to halt the planned National Insurance rise if they win the election.<br /> </p>
