In a saucepan over a high heat, combine the margarine, water, sugar, dried fruit and bicarb and bring to the boil. Reduce the heat and simmer for 15 minutes. Remove from the heat and allow to cool. Chill in the fridge overnight.
The next day, preheat the oven to 170 C / Gas 3. Grease and line a deep round 23cm cake tin.
Into the chilled mixture add the eggs, self raising flour, mixed spice and cherries then mix well.
Bake in the oven for 90 minutes or until a skewer inserted into the centre comes out clean. Remove from the oven and cool on a cooling rack.