Chiltern trains have already shaved 20 mins off the time from central Birmingham to London further diminishing any time benefit, Ha ha ha, offered by HS2 and are expecting further time savings with improved signalling. In addition Chiltern Trains, owned by Deutsche Bahn, ( is any one surprised it it not owned by a UK concern?) built their own station at Banbury for half the cost of the estimate put forward by the stunningly useless Network Rail.
With HS2s costs rising 30% every 2 years and the DfT having been caught out, once again, using out of date, 6 year old skewed to them, test criteria and three year old, out of date estimates for current costs, how much longer will we have to wait until HS2 goes off the rails for good and a line is drawn under the 2 billion already wasted. No wonder they don't want to publish any accounts. Had we spent that money wisely we would already be halfway to the extra capacity they, for some reason, crave, without the necessity to pour further concrete all over the UK countryside.
Civil servants should pay the price for their fcuk ups not the taxpayer. It is time to sweep the Dft clean and start again. Already £30 billion in debt and they want to add more!
It is now quite clear, even to the Public Accounts Committee just how big a white elephant HS2 is.
With respect to the OP, his question really should have been at least a £100 billion one and probably considerably more.