The Harrow Foundation also runs an independent Grammar School in Harrow , called the John Lyon School , and several international schools . Harrow School , commonly known simply as `` Harrow '' , is an English independent school for boys situated in the town of Harrow , in north-west London . There is some evidence that there has been a school on the site since 1243 but the Harrow School we know today was officially founded by John Lyon under a Royal Charter of Elizabeth I in 1572 .