Turn oven on to 180.

Melt the first five ingredients together in a saucepan , stirring.  Take off the stove and leave to cool.  ( This is important as the biscuits will cook nice and crisp)  Sift the flour and baking soda together and, if you like, a teaspoon of mixed spice or ginger or cinnamon. Add the raisins to the flour etc and then stir the lot into the melted mixture. 

Roll the mixture into small balls and place on a cold ungreased oven tray,  flatten them slightly with the hands, leaving room for some spreading.  Flatten more with a fork that has been dipped in water, so you get a ridged effect.

Bake for 15 minutes until they are rich golden brown. Tke out leave to cool. As they cool they will harden.