Grease 2 baking trays. Sift flours and salt into a large bowl, tipping in any bran left in the sieve. Sprinkle the yeast onto the milk to dissolve.
Rub butter into flour mixture. Stir in sugar, sultanas, currants and cinnamon. Make a well in the centre; pour in the yeast mixture. Mix dry ingredients into the liquid, adding a little more milk, if needed, to make a soft dough.
Turn dough out onto a lightly floured work surface; knead for 10 minutes until smooth and elastic. Place in a lightly greased bowl, cover with a cloth and leave to rise in a warm place for 1–2 hours or until doubled in size.
Turn dough onto the floured work surface and knock it back. Knead for 2–3 minutes, then divide it into 10 equal pieces. Shape each piece into a round teacake.
Place teacakes on baking trays; cover with a cloth. Leave to rise in a warm place for 30–60 minutes or until puffy.
Towards the end of the rising time, preheat the oven to 220 degrees C. Uncover the teacakes and lightly brush the tops with milk. Bake for 10–15 minutes or until browned; transfer to a wire rack to cool a little. Serve warm or split them open and toast lightly. Teacakes are best eaten on the day they are made, but if they are to be toasted, they will keep for 1–2 days.