In 1639, John Mattock gave the rents and profits from nine acres of land for "the maintenance of an able and learned schoolmaster for instructing the children of the inhabitants of Hitchin in good literature and virtuous education for the avoiding of idleness, the mother of all vice and wickedness," a quotation which can now be found as a plaque above the school's main entrance.

The original school Mattock founded, Tilehouse Free School, suffered many hardships, including conflict with the locals between Mattock's preferred Classics-based curriculum and a more practical 'three Rs' style of education, substandard teaching and a large amount of debt.

It was revived, however, by Frederick Seebohm, a rich and influential Quaker, as a fee-paying mixed school with some scholarships available for the town's poorest inhabitants.

The school's traditions include form running, a relay race which takes place at the end of every term.

The first form running competition was held in 1920, and this remains the only state school in the country to maintain this tradition.