Pour boiling water over dates in a small bowl, and let stand until cool.
Measure flour, baking powder, bi-carb, salt and nuts into a small bowl. Stir to mix.
Cream the butter and white sugar together in a mixing bowl; beat in egg and vanilla. Add flour mixture to creamed mixture in three parts alternately with date mixture in two parts, beginning and ending with dry mixture. Spread batter into a greased 23x33cm baking or cake tin.
Bake at 180 degrees C for 30 to 40 minutes, or until an inserted wooden pick comes out clean.
To Make Topping: Mix coconut, brown sugar, butter and cream in a small saucepan over medium heat. Boil for three minutes. Spread over warm cake, and brown under the griller.