He was employed as a telegram messenger in the Ceylon Postal Department, where he joined the trade union movement.
[4] At the 3rd parliamentary election held in April 1956 was elected as the third member from Colombo Central, a multi-member constituency, beating Dr. M. C. M. Kaleel of the United National Party by 46 votes into fourth place.
[5] On 7 July 1959 he resigned from the Sri Lanka Freedom Party and left the government, along with Philip Gunawardena to form Mahajana Eksath Peramuna (People's United Front).
[7] In 1965 Mahajana Eksath Peramuna joined with the United National Party to form a government under Prime Minister Dudley Senanayake.
At that point Themis left politics and commenced a career in printing and publishing.