Unlike the modern day, rich foods in a traditional household would have consisted of sugar, fat, flour and eggs. Now I can't imagine in the 15th century (first records of pancake day and pancake tossing) they cared about intolerances or that a need for gluten and dairy free existed but, fast forward a few hundred years, or a wee bit more, and there is most definitely a need.
I spend time in primary schools encouraging children to cook and, increasingly, I seem to come across more and more food allergies and intolerances including coeliacs. As a direct result, I am very aware of the difficulties that families have at festive time -- most shop-bought Christmas cakes and puddings will contain gluten.