Boris Johnson has confirmed that the £88bn HS2 rail line has received the "green signal," arguing that the "exploding costs" are outweighed by its "fundamental benefits". In a move that will divide opinion among Conservative MPs, the Prime Minister said the project will go ahead after a review made the "clinching case" in its favour. Speaking after the Cabinet this morning signed off on the decision, Mr Johnson told MPs that HS2 will bring a "vast increase in capacity" and enable the Government to press ahead with Northern Powerhouse Rail. Facing down criticism from his backbenches, Mr Johnson said the UK"s "great musculoskeletal problem" with transport could not be solved without major investment....