Preheat the oven to 180C/350F/gas mark 4
Use an 18cm/7 inch cake tin.
Grease and flour the cake tin. Sift the flour and baking powder. Rub in butter until the mixture resembles fine breadcrumbs. Add sugar, orange rind and grated carrot. Mix thoroughly, then add sour cream orange juice and milk. Spoon into the prepared tin and bake for 1 hour and 10 minutes. Cool on wire rack.
