During the era of former Headmaster, Mr. S.L.A. Ratnayake, the OBA was established in 1977. The Colombo branch was formed in the year 1990 and was subsequently amalgamated with the main body which evolved to what is in existence today.
The OBA is made up of many generations of boys who studied at S. Thomas’ College, Bandarawela since 1942. The Association is run by an Executive Committee, which is elected annually at the AGM. It provides an opportunity for old boys to reminisce and to keep abreast of events organized annually and also to assist the college in many development initiatives.
Through the OBA many Thomians have re-established contact with the 'Alma Mater',grown many folds and with substantial number of old boys becoming actively involved in a variety of projects to improve the facilities in the school. Over the years, old boys have assisted the college in many ways through the projects undertaken by the OBA.
The OBA is the ideal vehicle for those who wish to give something back to the College.