Preheat oven to 180°C. Grease a 22cm round baking tin and line it with grease paper.
Cream butter, sugar and essence until light and fluffy. Then add the eggs, one at a time, beating well after each addition.
Beat in orange and lemon rind. Fold in sifted flour alternating it with combined milk and fruit juice. Should the batter begin to curdle, sprinkle in a little flour. You should begin and end with flour.
Transfer mixture to the prepared cake tin and bake for 35-40 minutes or until cake is cooked through when tested with a skewer. Leave the cake in the tin for about 10 minutes then turn out onto a wire rack to cool.
For the icing, beat icing sugar, butter and 1 tablespoon lemon juice until smooth or it has a spreadable consistency. Add more juice as required, and rind last.