I agree Simon, the NHS is far from perfect, well that is an understatement, it is, frankly, mismanaged. This is not the fault of the front line Staff of course, but, despite your two year old graph, the Service has been cut, under funded, I still stand by that, relentlessly for decades, under a " Labour" Government, but really harshly since 2010 under the Conservatives.
Huge savings could be made by getting rid of the crap Management, and employing people dedicated to delivering the Service as it was envisaged in 1948. Yes, the money invested as a percentage of GDP may have to increase somewhat, but the Management I refer to are a hindrance to running an efficient Service, fit for purpose. Most have been employed to simply carry out the cuts. And these people are hugely expensive.