Butter an 8" by 4 1/2" bread tin and line it with baking parchment. Set aside. Measure the yeast, warm milk and honey into a bowl. Let sit for 5 to 7 minutes. Add the oil, egg, 140g (1 cup) of the white flour. and 70g each (/2 cup each) of the strong whole wheat and dark rye flours. Beat on low with an electric whisk to blend. Increase speed to high and beat for one minute. Scrape bowl and beat for a further minute. Add the remaining flour (140g/1 cup)and the yogurt. Beat until well combined. Spoon into the prepared bread tin. Cover with greased paper or plastic cling film. Set in a warm place to rise until the dough reaches the edge of the pan, about 40 to 50 minutes. Preheat the oven to 190*C/375*F/ gas mark 5. Bake the bread in the preheated oven for about 45 minutes, until golden brown, well risen and the bread sounds hollow on the underside when thumped. Remove from the pan and allow to cool on a wire rack. Note - You can use all whole wheat instead of a mix of whole wheat and rye flours.