Unlike many miniature breeds that resemble their larger counterparts, this breed was not developed simply by selectively breeding the Rough Collie for smaller and smaller size. The original sheepdog of Shetland was a Spitz-type dog, probably similar to the modern Icelandic Sheepdog. This dog was crossed with mainland working collies brought to the islands, and then after being brought to England, it was further extensively crossed with the Rough Collie, and other breeds including some or all of the extinct Greenland Yakki, the King Charles Spaniel (not the Cavalier), the Pomeranian,  and possibly the Border Collie. The first Sheltie to be registered by the American Kennel Club was 'Lord Scott' in 1911. Shelties have a double coat, which means that they have two layers of fur that make up their coat. His research found that an average Sheltie could understand a new command in fewer than five repetitions and would obey a command the first time it was given 95% of the time or better.