Mix the flour, ginger and sugar thoroughly. Melt the butter in a saucepan and add the treacle and bring to the boil, stirring continuously. Turn off the heat and add the other ingredients, mixing vigorously with a wooden spoon. When it has cooled sufficiently to handle, scoop up a small quantity of the mixture with a dessertspoon and push off with a teaspoon onto a well greased baking tray or sheet. Flatten slightly with a fork and leave space between each one to allow it to spread. Cook at 160C/325F/Gas Mark 3 for 25/30 minutes. Use a palette knife to lift the biscuits off the tray and store in an air-tight container.