Put the flour and salt in a bowl and mix together. Grate the butter directly into the flour, dipping the end of the butter in the flour if you need to avoid clumping. Use a blunt knife and cut the butter in to the flour to mix, breaking up clumps but you still want the little pieces of butter in there.
Mix in the water so that the dough comes together - press together with your hands. Use a little more water if needed but the dough should be a little dry. Wrap the dough in plastic/cling wrap and refrigerate 30 minutes.
Meanwhile, melt the butter for the filling in a small pan. Remove from heat and add the currants, sugar, lemon zest, cinnamon, allspice, nutmeg and diced dried papaya or mixed peel. Set aside until ready to use.
Once pastry has chilled, preheat oven to 400F/200C and line a large baking sheet/tray. Roll out the pastry on a floured surface to approx 4-5mm/ ⅕in thick. Cut out circles 10cm/4in diameter and place around one tbsp of the filling in each.
Pinch together the sides of the circle of pastry to join it together, using a little water if needed to help it stick. They should feel pretty well filled, so not too much extra pastry but not about to burst open. Turn the pastry over so the join is on the bottom, put on the lined baking sheet and gently press down to flatten slightly. Repeat with the rest of the circles and roll out the trimmings of the pastry again to make more.
Once all of the Eccles cakes have been formed, make sure you seal up any breaks in the pastry and cut 2-3 small slits in the top of each.
Beat the egg and brush over the top of each then sprinkle on a little sugar. Bake for approximately 25 minutes until golden. Allow to cool before eating as the filling will be very hot.