Eton is a full boarding school. All pupils live at the school. It is one of four such remaining boys' public schools (the others being Winchester College, Harrow School, and Radley College). Eton has educated generations of British and foreign aristocracy and members of the Royal family, the most recent being Prince William and his brother Prince Harry. The list of graduates includes twenty former British Prime Ministers, including David Cameron and Boris Johnson. "The Good Schools Guide" has called the school "the number one boys' public school," adding, "The teaching and facilities are second to none." The school is a member of the G20 Schools Group. It is registered as a charity.