Preheat your oven to 350°F (175°C) and liberally grease a 9x5 inch loaf pan.

In a large mixing bowl, whisk together the flour, brown sugar, baking powder, and mixed spice until uniform.

In a separate bowl or large measuring jug, combine the Guinness stout, molasses, melted butter, and vanilla extract until the molasses dissolves.

Pour the wet mixture into the dry ingredients and stir gently until a batter forms, being careful not to overmix.

Fold in the raisins and mixed candied peel until they are evenly distributed throughout the batter.

Pour the batter into the prepared loaf pan and bake for 55 to 60 minutes, or until a toothpick inserted into the center comes out clean.

Remove the bun from the oven and immediately brush the top with honey while it is still hot to create a sticky glaze.

Allow the bun to cool completely in the pan on a wire rack before slicing to ensure it holds its shape.