David S Jayasekera was a Head Master and Sinhala teacher at S. Thomas' College, Mt Lavinia.
He completed S. S. C. and the London Matriculation Examination and entered the University of Colombo to gain a Diploma in Education.
[1] Mr. Jayasekera's career at S. Thomas' College, Mt Lavinia lasted 48 years from 1947 to 1995.
Gamini Fonseka was among those introduced to acting through stage plays produced by Mr. Jayasekera at S.Thomas' College.
[3] Marcandan in a letter to a newspaper refers to R. D. Gunaratne, Uthum Herat, Russell de Mel, Duleep Goonewardena and Devaka Fernando as students who would have made Mr Jayasekera proud[4] He ran the school stationery store referred to as the 'book cupboard' which he ran with the assistance of students among whom were Kesaralal Gunasekara (later a member of parliament and deputy mayor of Dehiwala Mt Lavinia).