Grease and base line a 900g loaf tin and preheat the oven to 180ºC, gas mark 4.
Heat the Diet Coke in a medium pan until boiling. Remove from heat and stir in dates, bicarbonate of soda, then stir in the cherries, cranberries and honey. Mix well and allow to cool.
Sift the flour with the spices, then add to the cooled date mixture. Stir in the eggs and nuts. Pour into the prepared tin and bake for 1-1¼ hours, or until a skewer inserted into the middle comes out clean, covering with foil if the cake becomes too brown.
Leave to cool in the tin. Store in an airtight container for up to 1 week.