When the chips are down, former Manchester mayor Andy Burnham knows exactly what to do: white, soft bread, folded, not cut; lots of butter, chips inside, with salt and malt – yes – malt vinegar. This is the proper northern chip butty. Red or brown sauce are modern interlopers and cutting the bread shows you up. I know. I am that soldier. And there’s nothing quite like it, and specifically filled with chippy chips. No variations please. Old traditions die hard and are the mark of authenticity in a world which is slowly faking itself into extinction.Burnham will need every…