1. Preheat the oven to 180C/355F/Gas 4.

  2. Heat the oil in a large frying pan over a high heat. Add the lamb and kidneys and fry for 2-3 minutes, until golden brown all over.

  3. Add the onions and carrots and fry for a further 3-4 minutes, until softened and golden, then remove from the heat.

  4. Butter an ovenproof casserole dish with a lid and line the base and sides with a layer of potato slices, seasoning with salt and freshly ground black pepper.

  5. Add the lamb cubes, carrots, onions, kidneys, herbs and season again with salt and freshly ground black pepper.

  6. Add another layer of overlapping potato slices.

  7. Add the Worcestershire sauce to the beef stock, then add to the casserole, pouring evenly over the potato layer, until the stock level reaches the bottom of the top layer of potatoes.

  8. Brush the top potato layer with melted butter.

  9. Cover with the lid and place into the oven to cook for two hours, then remove the lid and return to the oven to cook for a further 30 minutes, or until the potatoes are crisp and golden.

  10. To serve, spoon out generous portions onto warmed plates with a spoonful of pickled beetroot alongside.