Work the yeast, warm water, and part of the flour into a soft dough. Mix well, cover with cloth and leave in a warm place to rise. Sift the remaining flour into a basin with the salt. Cream butter and sugar, add the beaten egg and the saffron infused in a little warm water and combine with the yeast dough. Knead with the raisins and peel, put into a greased baking tin and leave to rise again. Put into a moderate oven and bake for 1-1 1/2 hours.