Thawisan died at 1.53am at Chulalongkorn Hospital. He had suffered from kidney disease for several years.

His Majesty the King has assigned Phra Vararaja Thinadda Mart to represent him at royally sponsored funeral rites for Thawisan at Wat Benjamabophit. The rites will span seven days, with a prayer ceremony starting at 7pm.

Thawisan was married to MR Busaba Kittiyakara and had one daughter, Suthawan Ladawan Sathirathai, who is married to caretaker Deputy Prime Minister Dr Surakiart Sathirathai. Thawisan remained single after his divorce. Born on January 26, 1923, in Songkhla, Thawisan gained admission to the first class of Thammasat University in 1938 after graduating from Vajiravudh College. After graduating from Thammasat at the age of 21, he began his career at the Foreign Ministry.

In 1954 he also earned a Diplome d'Etudes Superieures de Droit International Public from Paris University.

Thawisan worked in key positions in the foreign service in several capitals, including Paris and Brussels. His last assignment at the Foreign Ministry was as deputy director-general of the Protocol Department before his departure in 1968 to serve as deputy principal private secretary to His Majesty.

A year later he was promoted to His Majesty's principal private secretary, a position he retained for 26 years. He was later appointed to the Privy Council.