Beat the butter, caster sugar, self-raising flour, baking powder and eggs together until smooth. Grease 2 x 18 cm (7 inch) sandwich tins and line the bases with greased greaseproof paper. Spoon in the mixture and level the tops. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20–25 minutes. Turn out the cakes on to a wire rack and leave to cool.
Beat the butter, sugar and orange juice for the icing gradually together until light and fluffy, then stir in the rind. Use some of the icing to sandwich the cakes. Place on a cake board and spread butter icing thinly around the sides and thickly over the top. Sprinkle sugar strands over the top.
Knead the ready-to-roll icing until softened, then roll out on a surface lightly dusted with icing sugar. Trim to a 60 x 8 cm (24 x 3½ inch) rectangle. Scallop the top edge, using a plain 6 cm (2½ inch) biscuit cutter to cut semicircles out of the icing. Carefully press the strip of icing around the edge of the cake.
Knead the trimmings, shape into a 60 cm (24 inch) rope and stick around the base of the cake with a little butter icing. Trim the ends, if necessary. Spread the remaining butter icing over the icing rope to resemble a fur trim. Decorate with the jelly beans. Use plenty of writing icing to stick the fruit sweets on to the crown.