I guess your only chance for premium quality cream coloured flannel is either lightweight (Holland & Sherry have 10oz. or something like that) or having a mill weave it specially for you. You'd have to commission at least 60 meters, though. I'm not sure how high the demand is, but you could ask people here or at London Lounge who would be interested. If you manage to get enough people to order this should make for a very good price because there's no middle man. Maybe Pendleton still make cream coloured flannel in a heavier weight?