Preheat the oven to 180C/356F/Gas 4.
Grease and line a 2lb/900g loaf tin.
Cream together the butter and sugar, then beat in the eggs.
Add the flour and mix thoroughly adding the milk as it gets drier.
Add the ground ginger, marmalade, orange zest, stem ginger and ginger syrup and mix well.
Put the mix into the prepared loaf tin and bake for 30–40 minutes, or until a skewer inserted into the middle comes out clean.
Leave the cake to cool in the tin for 5 minutes, then remove and finish cooling on a wire rack.
Decorate with the peeled clementine if using.