In a large heavy-based saucepan, fry the bacon in two tablespoons of olive oil. When the bacon is crisp and has released some natural fats, add the onions, celery, carrots, garlic, thyme, bay leaves and oregano and cook over a medium heat until the vegetables have softened and taken on a little colour. Add the tinned tomatoes, tomato purée, anchovy essence and Worcestershire sauce. Stir to combine.
Meanwhile, in a large frying pan, heat a little olive oil and fry off the mince in small batches until browned. While the meat is frying, break up any lumps with the back of a wooden spoon. Remove the cooked meat from the pan and repeat, using more oil each time if necessary, until all the meat is used up. After each batch, add the meat to the sauce mix.
In the same frying pan, fry the chicken livers until brown and crusty (in a little more olive oil) and add the livers to the meat. Deglaze the frying pan with some of the red wine, scraping any crusty bits from the bottom, then pour this wine, the remaining wine and the stock into the meat pot.
Bring to the boil, reduce the heat and simmer, stirring from time to time, for about two hours. Season to taste. If the liquid reduces too much, top up with water. When the meat is tender, allow to cool, then refrigerate. When cold, lift off the solidified fat and discard. Freeze the mixture in small batches and use for stuffed tomatoes, bolognese, cannelloni, shepherd's pie, moussaka or lasagne.