Grease a large loaf tin. Put the flour, yeast, salt and sugar in a bowl. Mix the butter with the milk and the measurement water and add to the bowl. Mix with a round-bladed knife to make a soft but not sticky dough.
Turn the dough out on to a floured surface and knead for about 10 minutes until smooth and elastic. Place in a lightly oiled bowl, cover with clingfilm and leave to rise in a warm place for 1 hour or until doubled in size.
Tip the dough on to a floured surface and shape into an oval slightly shorter than the length of the tin. Drop into the tin and cover loosely with oiled clingfilm. Leave to rise for about 45 minutes until doubled in size. Brush the top of the loaf with a little milk and sprinkle with poppy seeds. Place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for about 30 minutes until risen and deep golden, covering with foil if the surface starts to brown too much. Turn out of the tin and tap the bottom of the bread; if it sounds hollow, the bread is cooked. If needed, return to the oven (out of the tin) and cook a little longer.