Put the flour, baking soda and salt into a bowl and stir briefly. Cube the butter, add to the bowl and rub in
Pour in 2 tablespoons of the water and mix, with a blunt knife, to a soft dough, adding more water only if necessary (do not add so much that the dough turns sticky)
Bring the dough together with your hands then turn out onto a lightly floured worktop and knead briefly until smooth. Flatten slightly, wrap and chill for 30 minutes to allow the glutens in the pastry to relax
Meanwhile preheat the oven to 200C/ 400F/ GM 6 and line a baking sheet with baking parchment
When ready to assemble make the filling: put the currants, sugar and nutmeg into a bowl, melt the butter and stir until combined
Roll the pastry out into a rectangle approx 18cm x 36 cm. Trim off any straggly edges then divide into 8 squares measuring approximately 9cm x9cm. If the dough does not roll out to these dimensions, ensure that is around 3mm deep, cut as many squares as possible, then press the leftover dough back together and reroll to cut further squares - aim for 8 squares in total
Divide all of the filling evenly between the eight squares of pastry dough, using a spoon to pile it into the centre of each one
Dip a pastry brush in some beaten egg and run it around the edges of 1 square of pastry to dampen. Gather two opposite corners of pastry up towards the centre and press together lightly. Gather the other corners up to the centre too, pushing the filling back into the centre as you do so. When all corners are gathered gently press the pastry seams together and draw the edges into the centre to form a circle
When all edges are sealed, turn the pastry over, so the seams are underneath and use lightly floured hands to form a circular shape. Use a rolling pin to slightly flatten each pastry (roll lightly once, then rotate the pastry and roll again. Repeat as necessary until the fruit becomes visible (each Chorley cake should be around 6-7cm at this stage)
Repeat steps 7-8 with the remaining squares of dough then brush each top with a little beaten egg and use a sharp knife to cut three slashes across the top of each cake
Bake for 12-15 minutes until golden