Preheat oven to 120 C / Gas 1/2. Grease and flour one 20x30cm baking tin.
Cream the butter and the sugar together until light and fluffy. Add the eggs, one at a time beating after each addition.
Dissolve the bicarbonate of soda in the butter milk and add it to the egg mixture, beating well.
In a large bowl mix the flour, dates, orange bits, walnuts and coconut. Mix to coat. Add the flour mixture to the creamed mixture and combine well. Mixture will be very stiff and may require mixing with your hands. Place mixture into the prepared pan.
Bake for 2 1/2 to 3 hours. Mix the orange juice and icing sugar together and pour over the hot cake. Let cake stand in tin overnight before serving.