Preheat oven to 400F/200C (conventional oven).
Sieve the flour, salt and baking powder into a large bowl.
Rub in the butter with your fingers until it resembles fine breadcrumbs.
Stir through the sultanas, sugar and grated lemon rind.
Beat the egg and milk together in a small bowl or jug. Add most of this to the dry ingredients and mix to form a soft dough. You may not need all the egg/milk mixture.
Roll out to about 2½ cm thick and cut into small rounds. Brush the tops with any remaining egg/milk mixture.
Place on a greased or lined baking sheet and bake for 10-12 minutes, or until golden on top.
Remove from the oven and place on a wire rack to cool.