Preheat oven to 170C (325F). Grease and line a 23cm x 13cm (9" x 5") loaf pan.
Sift flour, salt and spices together.
Cream butter and sugar until pale and fluffy, add orange zest and egg yolks one at a time, then add honey.
Fold in sifted flour and spices, alternating with orange juice, adding more juice if batter is too stiff. Stir through the walnuts.
Bake in loaf tin 40-45 minutes, checking with a skewer at the 40 minute mark.
Cool on wire rack before frosting.
FROSTING
Beat all ingredients together in a small bowl until fluffy, then frost the cooled cake.