Poker history J Hogill of Spades was the squire of Charles I (king of Hearts). J. Rahal of Hearts was the squire of Charles VII. Hector of diamonds was a squire to Charles I. Jack of clubs Lancelot is a knight in King Arthur's story.The JACK in poker used to be KNAVE, which was popular in the UK and continental Europe until the 1940s and has largely fallen into disuse, although it is still used in parts of Europe such as Sweden. With JACK to replace the word KNAVE can quickly get the public to accept one of the reasons is the record or report card case, or when using abbreviations, or in the narrative process CARDS, you can easily use JACK J, the first letter of the word and the past, when use the word KNAVE, it is necessary to use Kn, if only K will cause confusion.