After Sir K Seshadri Iyer, Rayalu Arokiaswamy Thumboo Chetty of Tiruchirapalli (Trichinopoly) became the Diwan of Mysore. His tenure as Diwan was for a mere seven-month-period.
Rājadharmapravīṇa T R A Thumboo Chetty was a Christian of the Roman Catholic denomination. He was a person well-known for his integrity and non-deceitful nature. I have heard many people praise his benevolence and upright character.
Starting his career from an ordinary post, Thumboo Chetty rose to a position of eminence through his integrity and competence. He joined the military wing of Madras as a clerk. Subsequently, he earned praise as an assistant to renowned barrister John Dawson Mayne, the then Secretary of the Madras Legislative Department. Mayne has authored an invaluable treatise about the Hindu Dharmaśāstras. After working as a District Munsif for a brief period in Bellary, which during those days was part of the Madras Presidency, Thumboo Chetty joined as Head Sheristadar in the Mysore Services and grew to the post of Chief Judge in 1884. He discharged his duties in this position for ten to twelve years and became popular.
Following the announcement, the administrative reigns of the Mysore Province were transferred to the royal family on 25th March 1881 and Rangacharya was appointed as the first Diwan. Around that time, a council was constituted for his assistance. This council consisted of:
- Thumboo Chetty
- Purna Krishna Rao
- Attupakam Ratnasabhapati Mudaliar
Apart from being a Senior Councillor for around twenty years, Thumboo Chetty handled the responsibilities of the Diwan when K Seshadri Iyer was unwell in 1900-01 and on other occasions, and proved himself competent.
Since he was a Christian by birth, rumours were rife that he wasn’t allowed to take part in the proceedings of the royal court and that there was no possibility of him being appointed as Diwan. However, it wasn’t long before these rumours were proven baseless.
Thumboo Chetty’s community follows a mix of both Hindu and Christian traditions in their social life. Their population is quite small. Without ever resorting to extreme paths, they stand for goodness and peace in society.
Thumboo Chetty was particularly interested in the management of public organizations such as the Arcot Narrainswamy Mudaliar Charities and the Devaraj Bahadur Charity Fund.
This is an English translation of the fourth essay in D V Gundappa’s magnum-opus Jnapakachitrashaale (Volume 4) – Maisurina Diwanaru. Edited by Hari Ravikumar.
 ‘Rāja-dharma-pravīṇa’ was the title given to Thumboo Chetty. It loosely translates into ‘skilled in the code of conduct for rulers.’
 Mayne was the Assistant Legal Secretary to the Madras Government (1860–72) and also served as the Advocate-General of Madras (1862–72)
 A Treatise on Hindu Law and Usage (1878)
 A group of texts that deal with dharma; they prescribe duties, responsibilities, ethics, and other socio-religious practices that Hindus ought to follow
 District Judge
 Register General of the High Court
 According to the Rendition Act of 1881, the princely state of Mysore was reconstituted and restored to the Wodeyar dynasty, with Chamarajendra Wodeyar X at the helm
 His name is also spelt Rungacharlu
 Thumboo Chetty was a Senior Member of the Council of the Maharaja of Mysore (1881–95) and Senior Member of the Regency Council of the Regent Maharani of Mysore (1895–1901).