The Slaughtered Lamb has become well known from the movie "An American Werewolf in London" where two N.Y.U. students are attacked outside the pub, during the English leg of the European tour.

Two American backpackers, David Kessler and Jack Goodman, backpack across the moors in Yorkshire. As darkness falls, they stop for the night at a pub called the "The Slaughtered Lamb". Jack notices a five-pointed star on the wall. When he asks about it, the pubgoers stop talking and become hostile. The pair decides to leave, although the pub landlady insists they "can't let them go". Instead of changing their minds, the local clients only warn them to keep to the road, stay clear of the moors and beware of the full moon.

The original Slaughtered Lamb was a pub in a small town just north of London, cursed with the bloodline of the Werewolf. The inhabitants of East Proctor would sacrifice a lamb of their flock and smear the blood over the doors as part of a ritual to ward off the evil spirit of the Werewolf. A pentangle was also erected as a sign of respect so that the Werewolf would not tresspass on the property of the bearer. These same rituals were practiced at the local town tavern and it became a standard way of life for the local people.

More Info: en.wikipedia.org