Preheat oven to 180 C / Gas 4. Grease and flour two 20x10cm loaf tins.
In a large bowl combine the flour, dark brown soft sugar, caster sugar, pumpkin puree, oil, coconut milk, bicarbonate of soda, salt, ground nutmeg and ground cinnamon. Mix until all of the flour has been incorporated. Fold in the walnuts and desiccated coconut. Pour batter into the prepared tins.
Bake at 180 C / Gas 4 for 1 hour and 15 minutes or until a skewer inserted in the centre comes out clean. Remove from oven and cover loaves with foil tightly. Allow to steam for 10 minutes. Remove foil and turn out onto a cooling rack. Tent lightly with the foil and allow to cool completely.