Preheat the oven to 180°c / gas 4. Grease a 1lb loaf tin and set aside.
Using an electric whisk, beat the butter and sugars together until light and creamy.
Add the eggs and combine together, stir in the treacle and mix until all combined.
Fold in the flours and ginger alternately with the milk and mix until all combined.
Pour mixture into the loaf tin and bake in the oven for 35-40mins, until a knife inserted comes out clean. Leave cake in the tin for 10mins, then turn out onto a wire rack to cool completely.