Set in 50 acres (20 ha), the school's site is a mixture of old and new, with mid-Victorian architecture complemented by a Science Centre,[2] and modern classroom blocks and boarding houses.

He had a dual purpose in founding the school - to offer free education for the sons of poor clergymen and to provide a choir for his large church.

Since the 1970s St John's, while maintaining a substantial boarding community, has taken in an increasing number of day pupils and in 1989 the first Sixth Form girls entered the school.

After the Second World War, St John's was fortunate to attract the interest of the Viscount Montgomery of Alamein, himself the son of a clergyman, who was chairman of the governing body from 1951 to 1966.

Haslewood and Gloucester are both located in the heart of the school on the quad, whilst Hawkins shares its building with Churchill, opening its doors to pupils for the first time in September 2019.

The school competes on a circuit across a wide variety of sports, and some pupils have gained representative honours at county, national and international level.

[5] Rugby, football, hockey, netball and cross country are major sports at St John's, alongside cricket, athletics, tennis and swimming during the summer months.

[6] The school offers the following as additional competitive sports: badminton, biathlon, fives, golf, rounders, sailing, skiing, squash, shooting.

[6] Pupils also have the opportunity to participate in recreational sports, including Pilates, Zumba, indoor rowing, volleyball, wakeboarding and off-road cycling.

From Japanese to chess, from honing cricket skills to building a hovercraft or philosophical debates, there is an extensive list of opportunities, as well as art, music, drama, the combined cadet force, Duke of Edinburgh award and the school's community service unit.