Preheat oven to 375 degrees F (190 degrees C). Grease a 9x13 inch pan.
In a saucepan, combine the water, butter, sugar, nutmeg, mixed spice and fruit. Stir over medium heat until the butter is melted and sugar is dissolved. Bring mixture to a boil, then simmer for 3 minutes.
Remove from heat and cool slightly until lukewarm. Stir in baking soda.
Sift flour into a large bowl and make a well in the center.
Pour the fruit mixture into the flour, and mix together until blended.
Pour batter into prepared pan, smoothing surface with the back of a spoon.
Bake in the preheated oven for 75 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool in the pan for 5 minutes, then turn out onto wire rack and cool completely.
