It is run under the joint trusteeship of the Roman Catholic Diocese of Portsmouth and a religious order of teachers, the De La Salle Brothers.

Boaters were allowed to be worn by Sixth Form students, and boarders wore grey suits instead of the normal weekday blue on Sundays when going to Mass and Benediction.

[1] Following a trend set by many independent boys' schools, and first begun by Marlborough College in 1968, girls were admitted in 1970, initially into the sixth form and then in subsequent year groups from 1978 onwards.

In 1992, the Brothers withdrew from the day-to-day running of the school, though remaining trustees, and the first headmaster who was not a member of a religious order, Anthony McCaffrey, was appointed.

The Boarding Houses and Dormitories were later removed or converted into classrooms, and the swimming pool was demolished due to building problems, and the area given over to serving as the school's Sixth Form Centre after a refurbishment.

As an Arts College St Peter's was shortlisted, but not selected, for the 2008 Sky1 TV programme Hairspray: The School Musical, with students being interviewed and auditioned.

In 2008 St Peter's School made it to the National Theatre Connections final round, with Sixth Form student Oliver Biles directing the company.

A circular memorial to mark the motoring and aviation pioneer Charles Rolls, was unveiled in 1981 and is situated in the bottom corner of the lower playing field at the Southbourne site of St Peter's School.