It descends from a charity school founded by Westminster Benedictines before the Norman Conquest, as documented by the Croyland Chronicle and a charter of King Offa.

The school motto, Dat Deus Incrementum, quotes 1 Corinthians 3:6: "I planted the seed... but God made it grow.

During the mid-17th century, the liberal philosopher of the Enlightenment, John Locke, attended the school, and seven UK prime ministers also then attended, all belonging to the Whig or Liberal factions of British politics: Henry Pelham and his brother Thomas Pelham-Holmes, Charles Watson-Wentworth, James Waldegrave, Augustus Fitzroy, William Cavendish-Bentinck, and John Russell.

[22] In 1540, Henry VIII ordered the dissolution of the monasteries in England, including that of the powerful Abbots of Westminster, but personally ensured the School's survival by his royal charter.

[25] Queen Elizabeth frequently visited her scholars, although she never signed the statutes or endowed her scholarships; 1560 is now generally taken as the date that the school was "founded".

[27] It was Richard Busby,[28][29] himself an Old Westminster, who established the reputation of the school for several hundred years, as much by his classical learning as for his ruthless discipline by the birch, immortalised in Pope's Dunciad.

Busby prayed publicly up School[30] for the safety of the Crown, on the very day of Charles I's execution, and then locked the boys inside to prevent their going to watch the spectacle a few hundred yards away.

Busby also took part in Oliver Cromwell's funeral procession in 1658, when a Westminster schoolboy, Robert Uvedale, succeeded in snatching the "Majesty Scutcheon" (white satin banner) draped on the coffin, which is now held in the library[31] (it was given to the school by his family three hundred years later).

In 1679, a group of scholars killed a bailiff, ostensibly in defence of Abbey's traditional right of sanctuary after the man had arrested a person connected to the college.

There followed a scandalous public and parliamentary dispute lasting a further 25 years, to settle the transfer of the properties from the Canons of the Abbey to the school.

The Dean of Christ Church, Oxford, and the Master of Trinity College, Cambridge, were also ex officio members of the school's Governing Body until 2020.

She wrote to John Vickers, the OFT director-general, saying, "They are not a group of businessmen meeting behind closed doors to fix the price of their products to the disadvantage of the consumer.

In 2013 the school collaborated with the Harris Federation to set up a selective, mixed sixth-form academy, with entrance priority being given to those from disadvantaged backgrounds.

Harris Westminster Sixth Form opened nearby in 2014; pupils of the academy share some lessons and facilities of the school.

In May 2013, the school was criticized for staging an auction involving the selling of internships to fund bursaries, resulting in adverse press coverage.

Just outside the abbey precincts in Great College Street is Sutcliff's (named after the tuck shop on the site of the building in the 19th century), where Geography, Art,[58] Theology, Philosophy and Classics (Latin and Ancient Greek) are taught.

[72] This listed Art-Deco building adjacent to the school's playing fields at Vincent Square has been converted into a Sports Centre.

The pupil who gets the largest weight is awarded a gold sovereign (promptly redeemed for use next year), and the Dean begs for a half-holiday for the whole school.

[106] The School commemorates its benefactors every year with a service in Westminster Abbey in Latin in which the Captain of the King's Scholars lays a wreath of pink roses on the tomb of Elizabeth I: the service alternates between Little Commem, held in Henry VII's Chapel and involving just the King's Scholars, and the Big Commem, to which the whole school community is invited.

Since the monastic Christmas revels of medieval times, Latin plays have been presented by Scholars, with a prologue and witty epilogue on contemporary events.

Today, the play is put on less frequently, any members of the school may take part, and the Master of the King's Scholars gives the Latin prologue.

The 1938 play caused a diplomatic incident, with the German ambassador withdrawing after being offended by the words Magna Germania figuring in extenso on a map of Europe displayed.

[112] The premier Leander Club at Henley, founded in London by a number of Old Westminster rowers, later adopted it, although they call the colour cerise.

[118] During the 1840s at both Westminster and Charterhouse, pupils' surroundings meant they were confined to playing their football in the cloisters,[119] making the rough and tumble of the handling game that was developing at other schools such as Rugby impossible, and necessitating a new code of rules.

By 1867 the Football Association had chosen in favour of the Westminster and Charterhouse game and adopted an off-side rule that permitted forward passing.

[127] Two independent reviews were commissioned after national campaigns from Everyone's Invited and Black Lives Matter unearthed evidence of rape culture and racism at Westminster School.

The report also recommended training for housemasters, matrons, and tutors on managing pastoral issues including mental health.

Signatories complained that Westminster did not include any black authors in their curriculum and overlooked Britain's role in the slave trade.

[134] In March 2022, Challenge Consultancy published a Race Review of Westminster School that found "continued denial of the racism and the invisibility of the issue".

[128] 25 recommendations included the recruitment of "diverse teaching staff," a publicised racial harassment policy, and an increased offer of counselling for victims.