1. Bring the milk just about to the boiling point (you can do it in a microwave), leave to cool to the body temperature. Whisk the water and yeast together in a large bowl or in a standing mixer. Add the cooled milk and sugar and whisk it into the water and yeast mixture.
2. Add the flour to the liquid and stir in using a spatula. Scrape the side of the bowl and continue mixing until no dry flour remains visible. Distribute the butter in 8 or 10 pieces on the dough. Beat with an electric mixer or in a standing mixer with the dough hook attachment for a couple of minutes. Let it rest for 15 minutes. Sprinkle in the salt and beat the dough on medium speed until it is smooth and elastic, about 5 minutes. Transfer the dough into an oiled bowl, turn it over so that the top is oiled, and let the dough prove until it is almost doubled in bulk, about 45 minutes.
3. Scrape the dough onto a floured surface and flatten to a disc. Fold the two sides in to overlap at the middle, then roll the top towards you all the way to the end. Turn it over, flatten and repeat.
4. Return the dough to the bowl smooth (bottom) side up and let it rise until fully doubled, 30–45 minutes longer, depending on the room temperature.
5. In the meantime prepare a 13” Pullman tin or a 13” ordinary loaf tin by buttering it thoroughly, including the lid, and spraying or brushing with vegetable oil.
6. Turn the dough out to a floured work surface and divide it in half. One piece at a time, pull the dough to a rough rectangle and tightly roll it from the farthest long end towards you, swiss roll-style, pinching the end of the dough to seal. Leave the pieces of dough on the work surface seam side up and cover loosely with a cloth or oiled clingfilm. Let it rest for 20 minutes.
7. To form the loaf, place both pieces of dough 5mm away from each other on a floured work surface. Grasping one of the short ends with each hand, twist the dough in opposite directions to make an interlocked spiral. Slide both hands, palms upward, under the twisted dough and invert it, seam side down, into the prepared tin.
8. If using the Pullman tin, slide the cover about 2/3 of the way across the top of the tin. If in an ordinary tin, place it in an inflated large plastic bag (just blow into it and tie the ends!). Let the loaf proof until it is about 2.5cm away from the top of the tin.
9. Set a rack in the lower third of the oven and preheat to 200C/400F/gas mark 6.
10. Once the dough has risen so that it is only 1cm away from the top of the tin, slide the Pullman cover closed and/or place the tin in the oven. Turn down the temperature to 190C/375F/gas mark 5 and bake for 25 minutes in the Pullman tin, then slide the lid off and continue for another 10–15 minutes. In an ordinary loaf tin, just bake for 50 minutes, turning the tin around once in the middle of the baking time.
11. Remove the loaf from the oven and turn it onto a rack to cool. Wrap in cling film and keep at room temperature if using the same day or double wrap and freeze for longer storage.