Put both flours in a large mixing bowl and stir in the dried yeast and salt. Make a well in the centre. Put the milk and butter into a small pan and heat gently until the milk is warm and the butter is starting to melt. Remove from the heat and stir until the butter has fully melted.
Pour the warm liquid into the well in the dry ingredients and stir with a round-bladed knife to form a soft, slightly sticky dough. Turn the dough out on to a floured surface and knead for 7-8 minutes until smooth and elastic, adding a little more flour if it is sticky.
Put the dough in a clean, lightly oiled bowl and cover with clingfilm. Leave to prove in a warm place for 1 hour until the dough has doubled in size. Grease two baking sheets with the oil and dust lightly with flour.
Turn the dough out on to a floured surface, knead lightly, then divide into 16 evenly sized pieces. Roll and shape each piece into a ball and put 8 rolls (in two lines of four) on each baking sheet, spacing them roughly 1cm apart. Cover with oiled clingfilm and leave in a warm place for 30-40 minutes until almost doubled in size – the risen rolls should now be touching each other. Preheat the oven to 220ºC/gas mark 7.
Lightly dust the tops of the rolls with a little flour. Bake for 12-14 minutes until golden brown and the bases of the rolls sound hollow when tapped. Transfer to a wire rack and serve warm or cold.