Leading shares tended firmer throughout the afternoon session leaving the blue-chip index well placed to break through the 6,000 barrier tomorrow if it enjoys another day like today.Shares shrugged off the disappointment of a downward revision to third quarter gross domestic product (GDP) data. UK GDP rose 0.7% in the third quarter, revised figures show. Previously third quarter GDP growth had been estimated at 0.8%.Meanwhile, the minutes from the December meeting of the Bank of England's monetary policy committee (MPC) revealed that the committee was once again split three ways on what to do about interest rates and quantitative easing (QE). For the seventh month in a row MPC member Andrew Sentance voted for a rise in interest rates, while Adam Posen repeated last month's call for a £50bn boost to the Bank of England's QE programme.ARM Holdings was the star performer, though it came off the top towards the close. Software giant Microsoft is expected to announce a new operating system for hand-held touch screen computers that would use ARM's technology. FTSE 250-listed peer CSR, the bluetooth specialist, was also in demand on expectations that any Microsoft tablet device would use its technology.BSkyB was higher following news that business secretary Vince Cable has been stripped of his power to rule on News Corporation's takeover of BSkyB after telling undercover reporters he had "declared war on Rupert Murdoch". Cable kept his job on the insistence of LibDem leader Nick Clegg, but David Cameron called Cable's comments "totally unacceptable and inappropriate". Cruise operator Carnival continued to be buoyed by yesterday's well received fourth quarter results. Elsewhere in the travel sector, the absence of further snowfall is allowing airports to return to something approaching normal service, giving a boost to airline British Airways.British Land and Oxford Properties, the real-estate arm of Ontario Municipal Employees Retirement System (Omers) pension fund, have put pen to paper and signed contracts for a 50:50 joint venture to develop a new skyscraper in the heart of the City. The company, which mothballed the project during the recession, said the 736 ft (224m) 'Cheesegrater' is already generating strong interest from insurance and financial companies, and professional and corporate business sectors. It wil cost £340m and should be finished by the middle of 2014. Underwriter Catlin has raised the amount it expects to lose due to the New Zealand earthquake in September by US$10m (£6.5m) to $45m. The company said it was making the announcement 'in view of the increased interest in this event by the investment community.' The earthquake, which was in the Christchurch area, was estimated to have damaged about two thirds of the 160,000 homes there. Construction and engineering group Costain has emerged as one of the companies that has made an approach to struggling support services group Mouchel, sending the latter's shares higher. Costain announced today that it approached Mouchel's board on 2 December, with a view to making an offer comprising 0.5135 Costain shares for every Mouchel one, valuing Mouchel at 105.8p based on Costain's closing price yesterday. Sticking with the takeovers theme, shares in food producer Northern Foods sold like hot-cakes after the company confirmed that it had received an approach from Boporan Holdings, controlled by the owner of the Harry Ramsdens chip shop chain Ranjit Boparan. Northern added that it remains committed to its proposed merger with the Irish food group Greencore.Shares of Newmark Security plummeted after it said first half pre-tax profit more than halved but it remains optimistic for a better second half.Computer products developer Concurrent Technologies said sales in the second half of the year are expected to 'materially exceed' sales in the first as the recovery in the telecommunications and industrial sectors gains momentum.News that it has signed two new contracts with Deutsche Telekom and defence contractor QinetiQ was undoubtedly good news for collaborative software supplier Imaginatik, but it may have been the failure of the attempted coup by founder Mark Turrell that saw the company's shares zip higher. Turrell wanted to remove chairman Matt Cooper and finance director Shawn Taylor from the Imaginatik board and have himself reappointed. Despite Turrell owning 35% of Imaginatik the motions put by founder Mark Turrell to the requisitioned general meeting today were "conclusively" defeated, the company said, though it did not publish voting figures.AIM-quoted biopharmaceutical contract manufacturer Angel Biotechnology has secured a £1.53m manufacturing contract with Russian pharma company Materia Medica.FTSE 100 - RisersARM Holdings (ARM) 440.30p +9.12%Carnival (CCL) 3,059.00p +5.30%Schroders (Non-Voting) (SDRC) 1,482.00p +3.28%Schroders (SDR) 1,884.00p +3.06%Scottish & Southern Energy (SSE) 1,233.00p +2.49%Severn Trent (SVT) 1,491.00p +2.05%British Sky Broadcasting Group (BSY) 743.00p +1.99%British Airways (BAY) 273.60p +1.94%Eurasian Natural Resources Corp. (ENRC) 1,051.00p +1.94%GKN (GKN) 222.80p +1.83%FTSE 100 - Fallers3i Group (III) 330.00p -1.55%Smiths Group (SMIN) 1,255.00p -1.18%Inmarsat (ISAT) 678.00p -1.09%Amec (AMEC) 1,159.00p -0.77%Weir Group (WEIR) 1,798.00p -0.72%BAE Systems (BA.) 332.80p -0.69%African Barrick Gold (ABG) 591.00p -0.67%BP (BP.) 470.00p -0.52%Aggreko (AGK) 1,516.00p -0.52%Rolls-Royce Group (RR.) 647.00p -0.46%FTSE 250 - RisersCSR (CSR) 347.20p +8.64%Sports Direct International (SPD) 162.00p +5.47%Howden Joinery Group (HWDN) 103.70p +4.01%FTSE 250 - FallersGartmore Group Ltd. (GRT) 92.10p -3.66%Micro Focus International Plc (MCRO) 393.50p -3.10%Betfair Group (BET) 970.00p -2.41%