Although on a separate campus, it is regarded as the primary section of its famous sister senior school- Repton School.
The prep school for boys was founded in 1940 as a result of the drop of numbers and entries into Repton School- a result of travel inconvenience amidst uncertainties created in Britain during World War II which threatened the continuation of the Senior School. By establishing a junior section, it quickly guaranteed a secured number of students who were to enter Repton School for secondary education. The school appointed Mr. B.W. Thomas as its first Headmaster(1940–1947).
The school used Repton premises- 'The Cross House' at first for convenience partly because there was insufficient time and funds to secure and setup a proper campus, but mostly because it was unnecessary - Repton School has a large campus. By the end of the war, there were more than a 100 boys attending the prep school.However, the end of the war reduced the need for a prep school to secure numbers and the very existence of Repton Prep was threatened, and the school was forced out of the Repton school campus to new premises.