In addition to the other writeups in this node, Elephant and Castle is also a restaurant chain with locations scattered across Canada and the United States. The restaurants are styled after UK pubs, and serve much of the same traditional fare, British cuisine (oxymoron?), like fish and chips, shepherd's pie, not to mention bangers and mash, in addition to more American-style bar food. You have to appease the masses, I guess...

Beyond the menu, Elephant and Castle also carries a decent variety of imported beers and scotches.

As an addition or clarification to iain's explanation of the original term, the Elephant and Castle website has a differing explanation, although the concept is basically the same... it perhaps makes more sense, at least aurally.

Around the 14th century in far off merry old England, there lived a noble family from the Province of Castile in France. The family had a daughter whom they were to marry to a rich English prince. Then, as now, the rich and famous were the subject of gossip in all the inns and taverns. The comings and goings of the family from Castile were of great interest and everyone was awaiting the outcome of the situation.

Not too many people are aware, but England was bi-lingual at that time. It was common for the nobles to converse in French. For this reason, the Castile's daughter was know as L'Enfante de Castile - the child of Castile.
1

Addendum: Rose Thorn and I have come to the conclusion that the Castile in question is probably Spanish after all, so that explanation, wholly or in part, may or may not be bullocks.


1http://www.elephantcastle.com/restaurants_ec_description.html