Eton College, often referred to simply as Eton, is a British independent school for boys aged 13 to 18. It was founded in 1440 by King Henry VI as "The King's College of Our Lady of Eton besides Wyndsor". It is located in Eton, near Windsor in England, north of Windsor Castle, and is one of the original nine English public schools (which also includes Harrow School, Westminster School and Charterhouse School) as defined by the Public Schools Act 1868. Eton has a long list of distinguished former pupils. David Cameron is the nineteenth British Prime Minister to have attended Eton. Eton has traditionally been referred to as "the chief nurse of England's statesmen", and has been described as the most famous public school in the world. Early in the 20th century, a historian of Eton wrote, "No other school can claim to have sent forth such a cohort of distinguished figures to make their mark on the world". The Good Schools Guide 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. The school is headed by a Provost and Fellows (Board of Governors), who appoint the Head Master.