Combine the flour, 1 tablespoon caster sugar and a pinch of salt in a medium bowl. With a pastry blender or 2 knives, cut in the butter and margarine until the mixture resembles coarse crumbs. Stir 1 1/2 to 2 tablespoons iced water into the flour mixture until just combined. Flatten the dough into a round, wrap in cling wrap, and refrigerate for at least 1 hour.
Preheat the oven to 190 degrees C. Lightly grease a 23-cm pie tin. Combine the cherries, honey and lemon juice in a large bowl. Stir together 2/3 cup of sugar, the cornflour and allspice and toss with the cherries. Transfer filling to the prepared pie tin.
Roll the dough out to a 30cm round on a lightly floured surface. Place the dough on top of the pie, crimping the edges to seal to the rim of the pie plate. Brush the crust with the milk and sprinkle with the remaining sugar. Cut 3 or 4 slits in the crust with a sharp knife to act as steam vents, and decorate as desired.
Place the pie on a baking tray with sides to catch any drips and bake for 45 to 50 minutes or until bubbly and hot in the centre. Serve warm or at room temperature.