Combine the fruit, brown sugar and orange zest in a mixing bowl. Add hot tea and whiskey, if using. Stir well, cover and let soak for 4 hours or longer (up to overnight).
Preheat the oven to 350 degrees. Grease a loaf pan and set aside.
Add the flour, baking powder, spice and egg to the soaked fruit mixture, stirring until moistened.
Pour batter into the prepared loaf pan and bake until a toothpick inserted in the center comes out clean, about an hour.
Let cool in loaf pan. Slice while still warm and serve with butter.
Notes
If you don't have British "Mixed Spice", you can substitute gingerbread spice with a dash of coriander, nutmeg and allspice to come close to the taste.