Preheat oven to 200 degrees.
In a bowl, mix flour, baking powder, castor sugar, and salt.
Cut the butter into small pieces.
Using your hands, mix the butter into the flour mixture until the mixture looks like fine crumbs.
Add the fruit and combine.
Add the sour milk and milk and mix into a soft but not sticky dough.
Place dough on a floured surface and roll out.
Cut round shapes using biscuit cutters or a cup.
Brush the top with egg.
Bake for 20-25 minutes.
Remove from the oven and cool.