This is a simple but warming soup which tastes so good you will never want tinned again! I learned it at school and have cooked it for years, including at sea for 15 hungry sailors who loved it! This soup is hard to get wrong. Don't skimp on the flour and add a little extra milk if it's too thick. Make sure the flour is all incorporated before adding liquid. Use closed cup, button, chestnut, oyster or mixed mushrooms. Using dark gilled or flat mushrooms will make a darker soup.