Soak the breadcrumbs in the milk for 10 minutes, or until the milk has been absorbed.
Combine the beef, pork, allspice, pepper, flour, Worcestershire sauce and 1 tsp salt in a large bowl, add the milk-soaked breadcrumbs and use your hands to squash everything together for a few minutes until well combined.Roll the mixture into meatballs about the size of a cherry tomato. Chill for at least 30 minutes on a baking tray or plate. Note: the meatballs will keep covered and chilled for up to 24 hours, or frozen for up to 2 months.
Make the berry sauce by cooking the cranberries and sugar in a small saucepan over a medium heat with a splash of water for 5 to 8 minutes until the berries have burst and the sauce looks syrupy and glossy. Add a little more water if it becomes too thick. Leave to cool.
Heat the oven to 180C/160 fan/gas 4 and have a baking tray to hand. Heat a drizzle of vegetable oil in a large skillet or frying pan over a medium heat. Cook the meatballs, in batches if needed, for 8 to 10 minutes until nicely browned on all sides. Transfer to the baking tray and bake in the oven for another 10 minutes while you make the gravy.
Melt the butter in the same frying pan you fried the meatballs in (no need to wash it first), and stir in the flour. Sizzle for a minute or 2, then slowly add the stock, whisking to make a smooth sauce. Bubble for 2 to 3 minutes to allow the gravy to thicken, then add the cream and Worcestershire sauce and some seasoning, to taste. Tip the meatballs back into the gravy, scatter with the dill and serve with mash or chips, if you like, and the cranberry sauce.