Mix together the flour, oats,
bicarbonate of soda, cream of tartar and ginger in a bowl. Rub in the
butter or margarine until the mixture resembles breadcrumbs. Stir in
the sugar. Press the mixture down firmly into a greased 35 x 23 cm/14
x 9 in cake tin (pan) and bake in a preheated oven at 160ºC/325ºF/gas
mark 3 for 30 minutes until golden brown. Cut into squares while still
warm and leave in the tin to cool completely.