Or 1815, on the theory that Waterloo was a cusp that ended the Napoleonic wars, and freed enormous resources for infrastructure ... like rolling out the steam technology that was in vibrant development by Waterloo.
Unemployment was rising and food prices were so high that many people were on the verge of starvation (almost entirely due to political reasons). According to some Britain was close a French style revolution and the authorities cracked down very harshly on anyone advocating reform (see the Peterloo massacre and its aftermath).