you cannot make it up. this tory government started planning hs2 without doing a cost benefit analysis. they worked out the original cost to be 56 billion and now realise that it is way off the mark. they have now decided to do a cost/benefit review and will report by the end of the year.
in my humble experience the cost/benefit analysis of any project is done before a project begins and as it is being planned this is analysis is under constant review. if the costs go up far more than tolerances and benefits are reduced to below tolerances the project must be reviewed. the review should not take more than a few weeks if the objectives were being monitored like they should be. by anouncing that they will review and report by the end of the year, either they have not carried out the original analysis or they have not tracking them. either way it smells of incompetence. after having spent 4.1 billion pounds not a single bit of work done, they have decided to review.