In a medium saucepan, combine the raisins, sultanas, currants, brown sugar, butter and water. Cook over medium heat, stirring occasionally, until boiling. Boil for 20 minutes, then remove from heat and set aside to cool.
Preheat oven to 180 degrees C. Grease an loaf tin.
In a medium bowl, stir together the wholemeal flour, plain flour, baking powder, salt and cinnamon. Add the boiled ingredients along with the cooking sherry, mix until well blended. Pour the batter into the prepared tin.
Bake for 45 minutes in the preheated oven, then reduce the oven temperature to 160 degrees C and bake 15 more minutes, or until a toothpick inserted comes out clean.