Mix beef, pork, spring onion, oregano, parsley, garlic, Worcestershire sauce, salt and black pepper together in a bowl. Slowly add and mix breadcrumbs into meat mixture to desired consistency. Form mixture into balls, roll them in remaining breadcrumbs to coat, and arrange onto a shallow tray. Cover meatballs with cling film and chill at least 30 minutes.
Meanwhile, prepare the sauce. Heat 2 tablespoons olive oil in a large pan over medium heat. Cook and stir pancetta in the hot oil until browned, about 4 minutes. Add onion and garlic to the pancetta; continue to cook and stir until fragrant, about 1 minute. Stir carrot, celery and red pepper into the pancetta mixture; cook until the carrot softens slightly, about 3 minutes. Sprinkle basil, oregano, coriander and black pepper over pancetta mixture; stir to season evenly.
Pour wine over the pancetta mixture. Increase heat to medium-high and cook until the liquid reduces by about half.
Quickly stir tomato puree into pancetta mixture; add chopped tomatoes. Cook and stir the mixture until the tomatoes begin to break down into a sauce, about 5 minutes. Reduce heat to low and simmer until the sauce thickens, 60 to 90 minutes.
Heat 2 tablespoons oil in a large frying pan over low heat. Cook and stir meatballs in batches in hot oil until evenly browned and cooked through, 5 to 7 minutes; drain on a plate lined with kitchen paper.
Add meatballs to the sauce and continue to cook slowly for some 10 minutes or so until all heated through and ready to serve.