 He was also a member of the Travancore-Cochin Legislative Assembly from 1954-1956 from the Mavelikkara constituency.He was chosen as the First Speaker of the Kerala Legislative Assembly in the EMS Cabinet on 27 April 1957 and was Speaker till the dissolution of the first Kerala Legislative Assembly on 31 July 1959.As speaker, Thampi was known for his brevity and preciseness of his rulings.