Mix the flours, yeast and salt in a big bowl. Mix together the melted butter, sugar and water, then mix in with a cutlery knife.
Tip onto a lightly flour dusted surface and knead for 10 minutes (or use the dough hook attachment on your mixer).
Lightly grease the mixing bowl with some oil. Put the dough back in, cover the bowl with a clean tea towel and leave to rise until doubled in size.
Knock back the dough by gently kneading just 5 times to get the air out. Mould into a smooth oval and lift into a lightly oiled 900g/2lb loaf tin.
Cover the dough again with a clean tea towel and leave to prove until doubled in size again. Preheat your oven to 200°C (fan 180°C, gas mark 6).
Lift the tin onto the middle oven shelf and bake for 35-40 minutes, until you can lift the bread loaf from the tin and when you tap the base it sounds hollow. Cool on a wire rack.
