Ratnam was born on 10 March 1914 in Velanai on the island of Kayts in northern Ceylon.

[1] Ratnam joined the teaching profession and served as headmaster of the Moolai Senior Secondary School between 1934 and 1940.

[1] He stood as the candidate of Illankai Tamil Arasu Kachchi (ITAK), commonly known as Federal Party, in Kilinochchi at the 1965 parliamentary election.

[7][8][9][10] On 21 May 1976 Ratnam was delivering leaflets along with other leading Tamil politicians (A. Amirthalingam, V. N. Navaratnam, M. Sivasithamparam and K. Thurairatnam) when they were all arrested on government orders.

[11] All the defendants were acquitted on 10 February 1977 after a famous trial at bar case in which around 70 leading Tamil lawyers, including S. J. V. Chelvanayakam and G. G. Ponnambalam, represented the defence.

[15] Ratnam and all other TULF MPs boycotted Parliament from the middle of 1983 for a number of reasons: they were under pressure from Sri Lankan Tamil militants not to stay in Parliament beyond their normal six-year term; the Sixth Amendment to the Constitution of Sri Lanka required them to swear an oath unconditionally renouncing support for a separate state; and the Black July riots in which up to 3,000 Tamils were killed by Sinhalese mobs.

[3] He has written more than 12 books and contributed numerous articles on literary and cultural topics.