According to the official royal family website, the British monarchs claimed ownership of "all mute swans" in the nation as early as the 12th century. The birds were prized as a delicacy back then. The royalty apparently had the tradition of eating them during the holidays.

Queen, apparently, did not eat the swans anymore because they were a protected species now. But she still owned them. The queen still had an officially appointed Swan Keeper (Job title: Queen's Swan Marker) as long as she lived.

The swans were even dispatched throughout the world as gifts from the Queen.