The phrase Red Herring is used to describe something that provides a false or misleading clue, very often in a detective story. In the 1700s and 1800s herring was one of the most commonly caught fish in the seas around Britain. In those days it would be preserved by salting and smoking. This process would turn the herring a deep brownish red colour and heavily smoking it would mean it would get a particularly strong and pungent smell. The phrase’s origin lies in the early 1800s and hunt saboteurs. On hunt days the strong-smelling fish would be dragged along the hunt route and away from the foxes in order to confuse the hounds. The tactic was so successful that the phrase passed into common English usage.