I hope I am not being too optimistic too early but Muffin has now been on her new food for 3 days now and seems to be happy on it. I chose this brand for her
http://www.butcherspetcare.co.uk/choice/faqs/index.html and chose the fresh chicken one which states it has a minimum of meat content of 45% and is made with fresh chicken. No artificial additives or preservatives but has added vitamins. Muffin likes it and I am happier paying more but giving her a higher quality food. Will let you know how she gets on.