Another thought that occurs to me, this time in relation to school mashed potato. How was it that it was so nasty yet in different ways depending on the day it was served? And how could the powers that be have decreed that it ever be served with salad (Monday lunches)?
Here is how to make mashed potato that sings. Peel, chop into small pieces and boil your potatoes. Meanwhile, cut a small onion as finely as you can. When the potatoes are cooked, drain them, then throw in the onion, a large lump of unsalted butter, a glug of double cream, some salt crystals and freshly ground black pepper and mash away furiously. I use a potato ricer.
As you'll have gathered, this is not one of those recipes where precision in terms of quantities is required. What is necessary is thorough mashing and heat.
A final observation. "Mustard mash" is something you often now find in the kind of pub that serves lamb shank. It is my theory that potatoes and mustard do not go together. However, I have no difficulty with a dab of mustard on the side to go with the sausages that so often accompany mash: though it was only in the "Dandy" that they were ever stuck into the mash, as a feast for Tom Tum or Greedy Pigg.