Sautee the pancetta, onion, carrot and celery in the oil and butter over a low heat until they are slightly coloured and softened. Add the Pork and beef mince, cook over a low heat breaking up with a fork or wooden spoon. Season well with salt and pepper.
When the meat is browned add the red wine and deglaze the pan, increase the heat and continue to cook until all the wine has evaporated. Add the tomatoes, tomato paste and the bay leaves. With the heat on medium so the sauce is boiling gently, cover and simmer for 1 hour 45 minutes.
Remove the bay leaves before serving. Check seasoning.
Boil the tagliatelle in salted water, drain when al dente and add to the Bolognese. Toss well , place in the serving dish and finish with the parsley, a drizzle of olive oil and parmesan