Preheat the oven to 300 degrees F (150 degrees C). Grease a 9x5 inch loaf pan, and line with parchment paper or aluminum foil.
Combine the water, mixed fruit, sugar and butter in a saucepan over medium heat. Bring to a boil, stirring occasionally, and boil gently for about 10 minutes. Sift the flour, baking soda and mixed spice into a large bowl. Pour in the boiled mixture, and stir until well blended. Mix in the eggs. Pour into the greased loaf pan.
Bake for 90 minutes in the preheated oven, until a skewer or knife inserted into the top comes out clean. Cool cake in the pan for at least 10 minutes before removing.
