Combine the flour and salt in a large mixing bowl. Rub the butter into the flour, distributing it as evenly as possible. Stir in the yeast and sugar. Combine the water and milk in a small saucepan and warm over a medium heat.
Remove once warmed, then stir into the flour using a wooden spoon until you have a soft dough. Knead the dough on a lightly floured surface for 8-10 minutes until you have a smooth, elastic dough. Incorporate the raisins into the dough towards the end of kneading.
Preheat the oven to 210°C.
Grease a large loaf tin, then shape the dough into it. Cover with a piece of greased clingfilm and leave to rise in a warm place for 1 hour. Remove the clingfilm after proving and bake the bread for 30-40 minutes until golden and risen.
Remove from the oven and brush the top immediately with the extra tablespoons of milk. Allow to cool in the tin before turning out onto a wire rack to finish cooling. Once cool, slice into portions and arrange in a lined basket before serving.