Free Range Organic Chicken With Sweet Peppers and Tomato

8 free range organic chicken portions, generous, with skin and bone 1 onion, chopped 2 bell peppers, various colours, chopped 2 tablespoons olive oil 14 ounces tomatoes with juice, canned (1 tin) 4 tablespoons ketchup (made with real tomatoes!) 2 -3 tablespoons sugar...