[2] Before entering politics he had worked as a clerk in the Kerala State Road Transport Corporation.
[3] He is known for playing a crucial role during the implementation of decentralisation project in Kerala.
[4] Thankappan entered politics by his activism in the Communist Party of India from 1963.
[1] In the Second E. K. Nayanar ministry, he became the Minister for Local Administration from 2 April 1987 to 17 June 1991.
[5] During this period where V S Achuthanandan Government was formed, he acted as the pro-tem Speaker of the house.