Fry the onion and celery in half the oil over a low heat, until they start to soften, then add in the carrots and mushrooms for an additional couple of minutes. Turn into a large casserole or stewing dish.
Turn up the heat on the frying pan, add the rest of the oil, and then brown the meat in batches until it is well browned. Dust with flour for the final minute, then add to the casserole.
Tie the rosemary, bay leaves and thyme together, as a bouquet garni, and then add to the casserole with the remaining ingredients. Give a good stir, then pop on the lid and cook in the oven for about 2 hours, checking every half and hour or so and giving it a good stir. You may need to splash in a little more water (or wine!).
Remove the lid for the last 10 minutes of cooking, then remove from the oven and allow to rest for 10 minutes before serving. Serve with a buttery mashed potato with horseradish sauce mixed through.