• Season the lamb with salt and heat a large heavy based casserole dish with 1 tablespoon of olive oil. Over a high heat, fry off the lamb in batches, browning on all sides until caramelised all over. As you remove each batch and set aside, add a splash of water to the pan to deglaze it, and save these juices with the cooked meat. Cook off the rest of the meat using a further tablespoon of oil.
• In the same pan, add the pancetta with the final tablespoon of oil and cook until the fat renders  from the pancetta and is golden. Turn down the heat and add the onions, celery and carrot. Season and cook for 10-15 minutes, stirring regularly until very soft. If at any point the vegetables are catching, add a splash of water.
• Add the garlic and tomato purée and cook for a further minute, then add the flour and cook for 2-3 minutes.
• Turn up the heat, add the wine and allow to bubble up and cook off for 2 minutes, then add the tinned tomatoes, stock and herbs. Return the meat and reserved juices to the pan, bring up to the boil, then turn down to a bare simmer. Partially cover with a lid and cook for around 2 ½ hours until the lamb is falling apart tender and the sauce has thickened and reduced, stirring the butter beans in for the last 15 minutes. At this stage, taste and season with salt, pepper and sugar if you think it needs it. Make sure not to stir too vigorously as you want some nice big chunks of lamb. The ragu can also be finished in the oven.

• Serve with freshly chopped parsley as a garnish.

Tips for batch cooking:

If you’re planning on freezing this stew, freeze it at the stage before you add the butter beans, then when you defrost it, add them later to prevent them getting a funny texture.

When reheating the stew on the hob, add a splash of water to make sure it’s saucy and piping hot before serving.