Rinse beans. In a large pot combine beans and the 8 cups water. Bring to boiling; reduce heat. Simmer, uncovered, for 2 minutes. Remove from heat. Cover and let stand for 1 hour. (Or, place beans in water in pot. Cover and let soak in a cool place for 6 to 8 hours or overnight.) Drain and rinse beans. Wipe pot dry.
In the same pot brown lamb, half at a time, in hot oil; drain fat. Return all lamb to the pot. Add beans, carrots, sweet pepper, onion, bouillon granules, Worcestershire sauce, dried thyme (if using), garlic, and bay leaves to the pot. Add 4 cups fresh water. Bring to boiling; reduce heat. Simmer, covered, for 1 to 1-1/2 hours or until beans are tender.
Stir in chicken, tomatoes, salt, and fresh thyme (if using). Return to boiling; reduce heat. Simmer, uncovered, for 30 minutes more. Discard bay leaves. Skim fat if necessary. Season to taste with salt and black pepper.