Preheat oven to 190°C. Lightly brush a baking tray with a little softened butter.
Combine the self-raising and wholemeal flours in a small mixing bowl and stir in the salt. Mix the butter into the dry ingredients with your finger tips until well distributed. Add the sugar, raisins and mixed peel.
Pour in the milk while stirring the mixture with a fork. Add just enough to make a soft but not sloppy mixture (the actual amount of milk you need for this will depend on the absorbability of the flour).
Do not overwork the mixture. Stop stirring once it starts to come together.
Working quickly, arrange small piles of the mixture (about two rounded teaspoons each) on the baking tray, leaving 3cm space between buns to allow for some expansion.
Bake in the preheated oven for 15-17 minutes (depending on the size of the buns) or until they are lightly coloured.