Queen Elizabeth II promptly abdicates the throne and renounces any claims the House of Windsor has to it. The descendent of the once and future King are crowned and there is much rejoicing throughout the land.
King Arthur was a Briton, who were named "Welsh" by the Saxons. The House of Windsor was known at this time as the House Saxe-Coburg and Gotha. Windsor came from de-germanizing the name during WWI. The British royal family is German. The English are Anglo-Saxons, which are a German tribe, and are the people King Arthur fought against.