Business Green: The Conservative party will today seek to reinvigorate its environmental agenda with a high-profile pledge to ditch plans for a third runway at Heathrow in favour of a TGV-style high-speed rail network linking London, Birmingham, Manchester and Leeds. The party said that the 180mph line would aim to cut 66,000 flights a year from Heathrow by tempting domestic travellers onto trains capable of travelling from London to Birmingham in 45 minutes; London to Manchester in 80 minutes; and …