In a large bowl, cream together the butter and the 1 cup of sugar until light and fluffy. Combine the flour, baking soda, salt, cinnamon, nutmeg, and cloves; stir into the creamed mixture until well blended. The mixture will be dry. Stir in the carrots, raisins and chopped walnuts. Pour into a well-greased pudding mould. Cover the top with aluminum foil and tie it down with string.
Place the pudding mould into a large with about 5cm of water. Cover the pot, and bring to a simmer. reduce the heat to low, ans allow the pudding to steam for 4 hours over low heat. Remove from the mould. Serve with warm lemon sauce.
To make the lemon sauce, mix together 3/4 cup of sugar, cornflour and salt in a saucepan. Stir in the hot water, butter, lemon juice and vanilla. Cook over medium heat until thickened. Serve warm over the pudding.