Thanks for the replies,
They are both full working cocker spaniels, But i am just mistified why coco back is appearing darker - when they go back to their groomers, they have already had their monthly bath, and are not due a trim until 5th of january, I will ask her just what she thinks to the change in her colour. I only noticed just how dark her back has become and that she is looking more black there than anywhere else now. I really must update the photos - just havent had the time to take any new ones lately. I love walking my girls and they enjoy hours on our fields with me.