For the dough: Place the flour, sugar, salt and yeast into a large bowl of a stand mixer fitted with a dough hook. Making sure the salt and yeast do not touch. Then in a separate bowl whisk the four eggs together briefly so they are beaten and combined. Turn the mixer on, on a low speed and combine the dry ingredients for 30 seconds. Then pour in the beaten eggs and milk. Turn the mixer up to a medium-high speed and knead for 10 minutes, pushing the flour into the centre of the mixture every now and then,
Then with the mixer still running, add the butter one tablespoon at a time, waiting for each piece to be absorbed before adding another. This process should take around 10 minutes. Then knead for a further 3-5 minutes until the dough is no longer sticking to the sides of the bowl.
Pour into a large glass bowl and cover. Then leave in a warm place to prove for at least an hour until doubled in size. Your dough will be ready when it springs back slowly when pressed. Meanwhile, butter the base and sides of two 2lb loaf tins and set aside.
Then turn the dough out onto a clean worksurface and fold into itself a few times, to knock the air out. Then divide into 14 pieces, and roll each piece into a ball. Place 7 balls into each loaf tin - with 4 balls on the left-hand side and 3 balls on the right-hand side in the gaps. Then leave to prove again in a warm place for 45 minutes, until the dough has puffed up. Meanwhile, pre-heat the oven to 180C/160C Fan/Gas Mark 4.
To glaze: Once the loaves have proved, beat the remaining egg in a small bowl until combined. Then using a pastry brush, glaze over the proved dough. Then bake in the oven for 35 minutes until nicely browned on top. Leave in the tins to cool for 15 minutes, then turn them out onto cooling racks to cool completely.