Have the beef rolled and tied. Cut bacon into thin strips and put into casserole. Put in the meat. Slice the onions thinly and put round the beef. Add salt and pepper, depending on possible saltiness of bacon; add bay leaf. Heat together ale, stock and vinegar and pour over the meat. Cover tightly and cook at 300°F, 150°C, gas mark 2 for three and a half hours. The gravy is rich and delicious, and the meat has a good flavour when eaten cold or in sandwiches.