For the biscuits, preheat the oven to 180C/350F/Gas 4.
In a bowl, mix the dry ingredients together. Rub in butter and lard so that mixture resembles fine breadcrumbs.
Add just enough cold water to bring the mixture together to form a stiff dough (about 5-6 tablespoons). Refrigerate for 15-20 minutes.
On a lightly floured worksurface, roll out the dough to a thickness just less than a £1 coin.
Using a 9cm/3½in round cutter cut out biscuits from the dough. Prick the top of the biscuits all over to decorate, leaving a plain 5mm/¼in border around the edge.
Transfer to wire racks or baking mesh. Place the racks/mesh on baking trays and bake for 14-16 minutes, or until the biscuits are dry but not browned. Set aside to cool completely.
Serve the biscuits with chilled butter.