Season the lamb in a bowl, then toss in the flour. Heat 1 tbsp of the oil in a large flameproof casserole dish over a high heat and brown half the lamb pieces on all sides. Transfer to a plate, then brown the remaining lamb pieces. Remove to the plate and set aside.

Reduce the heat to medium and add the remaining 1 tbsp oil to the pan. Tip in the onion and carrot, and cook for 10 mins, stirring regularly, until soft and golden. Add the garlic, rosemary and tomato purée, and stir for 1-2 mins.

Return the lamb to the pan and pour in the wine and stock. Stir in the redcurrant the jelly and bring to a simmer. Reduce the heat to low, cover and cook for 2 hrs-2 hrs 30 mins, or until the lamb is tender. (Alternatively, tip into a slow cooker and cook on low for 6-8 hrs; or cook in a pressure cooker for 20 mins.) Once fully cool, the lamb stew will keep in an airtight container in the fridge for up to three days, or frozen for two months. Defrost in the fridge overnight before reheating until piping hot.

To make the topping, tip the potatoes into a pan, cover with water, bring to the boil and cook for 10 mins until softened slightly but still holding their shape. Drain and leave until cool enough to handle, then grate using the coarse side of a grater. Put into a bowl with the cheddar, half the melted butter and plenty of seasoning, and mix until well combined.

Heat the oven to 190C/170C fan/ gas 5. Transfer the lamb stew to a baking dish (ours was 20 x 30cm). Scatter the potato topping over the meat, and poke a few small rosemary sprigs into it. Brush with the remaining butter and bake for 35-40 mins until the topping is golden brown and the stew is bubbling at the edges.