S. Thomas' Preparatory School, Kollupitiya was founded on 17th May, 1938 by the late William Thomas Keble M. A. (Oxon) eminent educationist, scholar, author and lover of Sri Lanka. He arrived in the island in 1928 to join the staff of S. Thomas' College, Mt. Lavinia during the tenure of Warden Kenneth McPherson. The late W. T. Keble received his tertiary education at Keble College, Oxford which bears the name of his great grand uncle the noted hymn~writer and poet John Keble. His two books 'Ceylon Beaten Track' and the novel on Sigiriya reveal W. T. Keble's appreciation and love of Sri Lanka and its history.

The School is an Anglican (Church of Ceylon) educational institution and was founded during the episcopate of the Rt. Rev. Dr. Mark Carpenter-Gamier M A. (Oxon) D. D. who was the 6th Bishop of the Diocese of Colombo. The School owes much to him for his vision, wisdom and generosity in having rendered every assistance possible to Mr. W. T. Keble's venture to found it.

This institution which commenced in 1938 with a mere 95 boys on roll and a staff of 7 teachers, including the Headmaster the late Mr. Keble, has the enviable honour of being the first Preparatory School modelled on English Public School lines in Sri Lanka. This marked a truly pioneering venture in the history of education in the island, as Mr. Keble sought to remedy a conceptual void in the educational system by placing a new emphasis on the requirements and aspirations of the child of tender years between the ages of 5-11. The conceptual rationale underpinning Mr. Keble's vision for the establishment of such a school was the provision made for boys in their formative years to fully express their creative talents and faculties unfettered, unhampered and uncircumscribed by older and more mature students in their midst.

The School has over the years shed its preparatory school character due to the pressures of parents and the clamour for schools with the burgeoning population. In its present form, the institution provides education exclusively in the Sinhala and Tamil media up to the G.C.E. (Ordinary Level) in conformity with the educational policy of the State.

However, it is a private fee levying institution which is financially independent of all State control and is managed by a board of governors established by law as contained in the S. Thomas' College Board of Governors Ordinance No.7 of 1930. The Bishop of Colombo is the Chairman of the Board and thus retains the connection between the Church of Ceylon and the school.

Presently, the student population numbers over 1850 pupils on roll with a staff of over 80. As the institution approaches its seventieth year of providing a sound education to boys of all ethnic and religious backgrounds, it is certainly a far cry from the little school which began with less than a 100 students and 10 teachers. The school continues to nurture, train and equip students to face the multitude of challenges which confront them in a society which has altered radically from its relatively halcyon past. It thus plays a vibrant and meaningful part in the nation's progress, as it has always done during its brief but illustrious history.