I'd like to see them spend some quantitative easing money rebuilding British industry the way Germany did after the war.
This. A thousand times this. Unfortunately our industrial sector was largely decimated by Margaret Thatcher and our economy has been propped up by the service industries ever since. However borrowing to invest might take a while to catch on with the British public. Most of them are still convinced that you can't borrow your way out of a recession (you can, this being one of the basic rules of Keynesian economics)