This classic British dish is simple to prepare and bakes while you go about your occupations.

Place the rack in the bottom of the oven. Preheat the oven to 350°F (180°C).
In a deep ovenproof casserole or dutch oven with a lid, melt half the butter, remove from the heat and brush the bottom and sides of the pan with a pastry brush.
Spread about ¼ of the potatoes in the bottom of the pan. Cover the potatoes with half the onions, carrots and lamb. Season with salt and pepper, sprinkle half of the thyme and flour and top with a bay leaf.
Repeat the previous step with half of the remaining potatoes, the rest of the onions, carrots and lamb. Season with salt and pepper, sprinkle with the rest of the thyme and flour and place the second bay leaf.
Cover with remaining potatoes, melt the remaining butter and brush the potatoes.
Add the Worcestershire sauce to the broth and pour down the side of the pan. Cover and bake 5 hours . Uncover and grill for 5 to 10 minutes at about 8 inches (20 cm) from the grill until the potatoes are golden brown. Let stand 10 minutes before serving