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. This school closed in 1876. 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.

In 1889, this new school was first housed in the "Woodlands" building in Bancroft, Hitchin, owned by Seebohm's business partner Joseph Sharples, but moved in 1906 to its current location on Windmill Hill, also given by the Seebohm family, along with £1,000 towards the building and its maintenance.

Since 1960, there have been no more boarders; the dormitories were converted into the school's library in 1955, which used to be housed in the current staffroom.

It was awarded specialist Science College status in 2004. The head teacher is James Crowther who replaced Frances Manning. Frances Manning replaced Mrs Edwards at the start of the 2007/8 academic year.

In July 2011 it became an academy.

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. Gymnastics competitions are held every year, the first of which took place in 1914.

Founders' Day, honouring the original benefactors, has taken place every year since 1932.

The school occupies several buildings:

• The Main Block built in 1906, with extra classrooms and a dining room added in 1929, 1939 and 1958. This block is currently used for teaching Maths, History, Classics, Computing and Art. It also houses the school library, which formerly served as dormitories for boarding students. The Main Hall, used for plays and assemblies, is situated there.
• A Science and Gym Block built in 1972, which is used for indoor PE lessons and for the teaching of all three sciences
• The Lower Block built in 1978, which contains specialist teaching rooms for Design and Technology and is also used for English and Modern Foreign Languages
• Highbury House, a music and foreign language teaching area
• A Sixth Form Centre which features a common room and several teaching areas for those in the Hitchin Consortium
• Woodside, a new block of classrooms designated for the increased intake of Year 7 students, which was finished on 5 September 2018

The school is split into eight houses, with six established in 2004 and two added in 2018 to accommodate an expansion of the school.

• Joanna Haigh, physicist and academic
• Catherine Heymans, astrophysicist^[1]
• Emma Kennedy, English television actress, writer and presenter
• Pauline Pearce, politician and viral "Heroine of Hackney"
• Eileen Soper, artist^[2]
• Claire Tomalin, biographer and Whitbread Book Award winner

• Official site