I AM a keen follower of your column. It is available in major supermarkets. Buttermilk is the residue or liquid left over from milk churned into butter and then left to turn sour naturally. It is also available in major supermarkets.
Treacle is a sticky fluid remaining after sugar cane is processed.
It has a slightly bitter taste but with a sweetening power that is less than sugar. It is available in specialist cake shops. Muscovado sugar or Barbados sugar has a high molasses content and is moist and dark brown in colour. It is used in baking and in confectionery. This too is available at cake specialist shops.