Christian sees for himself the hydrogen-powered bus fleet introduced through the pioneering partnership between Surrey County Council and Metrobus [01:30] before discussing with Mark Walker the findings of the House of Commons Public Accounts Committee on the cancellation of the northern sections of HS2 [30:47].  Listeners then receive an update on Christian's new book - 'The Liberation Line' - which reveals the exciting yet forgotten story of the Allied engineers who rebuilt the railways of Normandy and beyond after D-Day to accelerate the defeat of Nazi Germany [30:05].  Finally, Christian notes the failed promises and ultimate demise of hyperloop [39:28].