How did an English police force become known as “Scotland Yard”?

In the tenth century, in an effort to stop hostilities between their two countries, the English gave a Scottish king land in London with the provision that he build a castle on it and live there for a few months every year. Seven centuries later, with the two nations united under one king, the land returned to English ownership. In 1829, the London police took up residence on the land, which by then was kown as Scotland Yard.