Combine water and chicken in large pot. Bring to the boil. Reduce heat and simmer until chicken is tender, about 1 hour. Using tongs, transfer chicken to strainer and cool, saving cooking liquid. Remove meat from bones in pieces.
Heat 2 tablespoons oil in heavy frying pan over medium heat. Add okra and cook until no longer sticky, stirring frequently, about 20 minutes; set aside.
Stir flour and remaining oil in heavy large saucepan. Cook over medium heat until deep golden brown, stirring frequently, about 6 minutes. Add 1 litre reserved chicken cooking stock, okra, smoked sausage, tomatoes with their juices, pepper, celery, garlic, bay leaf, salt, thyme, basil, cayenne and pepper. Cover partially and simmer until thickened, about 1 1/2 hours.
Spoon off any fat from surface of gumbo. Add chicken and simmer gently 15 minutes. (If preparing ahead, cover and refrigerate. Bring to simmer before serving.) Mound rice in shallow bowls if desired. Ladle gumbo over and serve.