From 1922:
Get half a dozen fresh herrings, remove the heads and tails, scrape and wash well, put them in a piedish, sprinkle with pepper and salt, cover with best vinegar, add a blade of mace and two bay leaves. Bake in a moderate oven until cooked through; when cold, remove the skin and bones, pack tightly into small jars, and pour oiled butter over the top. Keep in a dry place. This makes a nice relish for tea.