London's top stocks look set to drop more than 100 points in early dealing as investors consider this morning's news that the UK is heading for a hung parliament.In the UK election, the Tories are on course to be largest party but set to fall short of majority, as David Cameron's party fails to take many key target seats while Labour is pushing to form coalition with Lib Dems. The latest polls suggest the Tories will end up with 309 seats, Labour on 259 and the Lib Dems on 54. Part-nationalised lender Royal Bank of Scotland moved into profit at the operating level during the first quarter of 2010 as impairment charges fell, although there was still a small pre-tax loss. Operating profit for the three months to 31 March was £713m compared with a £1.35bn loss a year ago, but the bank lost £21m before tax. It had reported a £44m pre-tax loss a year earlier and made a profit of £134m during the final months of 2009.ITV warned that the market outlook for the second half highly uncertain as it reported a 6% rise in revenues. The broadcaster's revenues in the first half increased to £450m compared with £425m last time. Broadcasting and online revenues were also up 6% to £390m, while ITV Studios external revenues rose 7% to £60m (2009: £56m), with internal production revenues at £73m (2009: £75m).Underwriter Chaucer has estimated its net losses from the Deepwater Horizon rig disaster in the Gulf of Mexico at $25m. In a statement, Chaucer said the net loss to Syndicate 1084 arose from direct energy portfolio($20m) and $5m for the marine excess of loss account. The loss estimate is net of reinsurance and reinstatement premiums receivable and payable.