300g/10陆oz heritage carrots, cleaned and trimmed
2 large onions, cut into thick slices
900g/2lb potatoes, peeled and cut into 5mm/录in thick slices
2 tsp Worcestershire sauce
2 bay leaves
600ml/20fl oz fresh beef stock
sea salt and freshly ground black pepper
2 tbsp flour
100驳/3陆辞锄 butter
2 mutton kidneys, fat on
1kg/2lb 4oz boneless leg of mutton, cut into 2.5cm/1in pieces