Preheat the oven to 200 degrees celsius.
Combine the flour, salt, and sugar together in a large bowl.
Add the butter and rub together with your fingers until the texture resembles breadcrumbs.
Add the baking soda and mix to combine.
Pour in the milk and treacle, and mix quickly. Then fold over just until dough forms.
Tip the bowl onto a lightly floured surface and form the dough into a circle.
Pat down until the dough is 3-4 cm thick.
Use a sharp knife and cut the dough into 8 equal pieces.
Place the scones onto a greased baking sheet.
Beat the egg and then brush the top of the scones with it.
Place the baking sheet into the center of the preheated oven.
Bake for 10-12 minutes or until golden brown.
Allow to cool for a few minutes before serving.