Preheat oven to 180 C / Gas 4. Grease a 23cm cake tin and line with baking parchment.
In a large mixing bowl whisk together the sugar and the eggs until pale and fluffy, then gradually add the oil.
In a separate bowl sift together the flour, spices and baking powder. Fold into the wet ingredients then add the carrots, sultanas, walnuts, milk and salt. Transfer to the prepared cake tin and smooth the top gently.
Bake in centre of preheated oven for 70 to 90 minutes until a skewer inserted into the centre comes out clean. Remove from the oven and cool before slicing and serving.