The meat can be a combination of beef and pork. Adding smoked bacon works. Find your groove.
Heat some olive oil in the pot and brown the beef lightly on each side. If you can't do it all at once, do it in batches. Return all the beef to the pot. Add the onion, the shallots, the garlic, the mushrooms, all the tomatoes, the chilli and then pour in the Guinness. If it doesn't cover everything add a little water. Bring close to the boil, and there's likely to be a fair bit of foam from the Guinness. Turn the heat down until everything is simmering and then add the red wine, the tomato puree, the Lea & Perrins and the beef stock. Add a large pinch or grind of sea salt and black pepper. Give the sauce a good stur, lower the heat a little until the sauce is gently bubbling then leave for an hour or so.
When reheating stir in the basil and thyme.
Cook the tagliatelle as per the packet instructions. Serve with the ragu on the tagliatelle and plenty of ground pepper and parmesan on top.