Sift the flour and salt into a warm bowl. Blend the yeast, sugar and a little of the warm liquid and stir into the flour with the remaining liquid.
Knead for 8 minutes until smooth.
Leave to rise until doubled in size. Turn out and knead the dough lightly on a floured surface until smooth and elastic.
Roll out the dough into a rectangle piece 20" x 8". Divide the butter into three and dot one portion of butter over two thirds of the dough. Fold the dough into a third bringing the bottom unbuttered third up and folding the top third over. Seal the edges with the rolling pin. Repeat the process twice more using the rest of the butter.
Place the dough in an oiled polythene bag and refrigerate for 30 mins. Roll our the dough and repeat the rolling, folding and turning process without butter three more times. Return the dough to the polythene bag and the refrigerator for at least an hour.
Roll out the dough to 20 x 8 and cut in half lengthways ie into 4" strips. Then cut into 4" squares and then cut each square into two triangles.
Roll each triangle up starting at the longest edge and rolling towards the point. Tuck the end underneath, bend into a crescent shape and leave to prove in a warm place on a greased floured baking sheet inside an oiled polythene bag or covered with oiled cling film for approximately 20 mins.
Remove the cling film or bag and brush each with beaten agg and milk and bake in a hot oven 220C 425F Gas Mark 7 for 20 minutes or until puffred and golden brown.
Cool on a wired rack.