Heat 2 tablespoons of the oil in a large stock pot over medium-high heat. Add the pancetta or bacon, carrot, celery and onion, and cook, stirring, for 8 minutes until the vegetables are soft.
Add the sugar, garlic and tomato paste and cook, stirring, for 5 minutes or until the tomato paste starts to darken slightly. Transfer mixture to a large heatproof bowl.
Heat 1 tablespoon of the remaining oil in the pot. Cook the pork mince, breaking it up with a wooden spoon, for 5 minutes until lightly browned. Transfer to the bowl with the vegetables. Repeat in two more batches with the remaining oil and pork and veal mince and beef mince. Set aside.
Increase the heat to high. Add the wine to the pot and bring to the boil. Simmer for
5 minutes or until reduced by half. Deglaze the pot as you stir. Return the mince and veggie mixture to the pot. Add the tomato, stock, passata, Worcestershire, parmesan rind, lemon peel and bay leaves. Season well with salt and pepper.
Cover and bring to the boil, then reduce the heat to very low. Tilt the lid so the pot is partially covered, and cook, stirring occasionally, for 3 hours or until the sauce has reduced and thickened and is a glossy dark red colour. Serve with cooked pasta and grated parmesan.