It's still a pipe dream, but Hyperloop, the hyper-speed transportation system that uses a vacuum tube to propel passenger pods at mind blowing speeds, could be cheaper than HS2.

With the latest NAO report saying timescales and budgets for HS2 are unrealistic and need to be amended, should we be looking at this alternative technology for HS2 or even HS3 (the northern powerhouse crossrail)?