It was inaugurated on 23 September 1868, with 40 pupils, including 17 boarders, under the headship of Rev Richard Alliott, who remained at the helm until his death in 1899.

He also commissioned many of the campus's redbrick buildings designed in the arts and crafts style by architect and former pupil Herbert Ibberson, acquired the 100 acre sports fields and oversaw construction of the Memorial Hall, commemorating the Old Stortfordians who had died in the Great War.

In 1995 the college became fully coeducational, appointed its first female deputy head, Wendy Bellars, and opened a new co-ed Pre-Prep day school.

Since 2013 large parts of the college have been substantially redeveloped and expanded, including new premises for Alliott, Collett, Trotman and Rowe Houses, and an extension to the Prep School (during which workers excavated 2.5 tonnes of Hertfordshire puddingstone, one of the rarest rocks).

[6] After Kathy Crewe Read's choice to leave the College, John Maguire took over as Head in September 2024.

The report also stated that "the school is highly successful in creating an ethic of hard work and enthusiastic participation".

Since 2009 it has hosted an annual Festival of Literature, which is open to the public and includes events for local primary schools.

Speakers and performers have included Poet Laureate Simon Armitage, former Children's Laureate Anthony Browne, broadcasters Robin Ince and Michael Portillo, author and illustrator James Mayhew, art critic Andrew Graham-Dixon and the bestselling novelist Rachel Joyce.

Since 1992 it has been run by qualified librarians and is fully supervised for 70 hours a week to provide research and study facilities and assistance for pupils and staff.

[15] The Grade II listed Memorial Hall has been used for assemblies, concerts and special events since it was formally opened in 1922 by Sir Arthur Quiller-Couch.

Designed by architect Bertram Clough Williams-Ellis (creator of the Italianate village of Portmeirion in North Wales), it was built to commemorate the 62 former college boys who had died in the First World War.

Other facilities include the purpose-built Charles Edwards Centre, which houses ICT, physics and design and technology, and the Walter Strachan Art Centre, which has a sculpture studio, workshop, gallery space, IT suite, sixth-form studio and departmental library.