He then joined Waterloo College, London and Madras Christian College where he studied political science.
He received military training from the Palestinians in Lebanon. In 1979 K. Pathmanabha left EROS to form the Eelam People"s Revolutionary Liberation Front (EPRLF) and Premachandran joined him. Premachandran took on the leadership of EPRLF following the assassination of Pathmanabha by the Liberation Tigers of Tamil Eelam on 19 June 1990.
Premachandran was one of the ENDLF/EPRLF/TELO/TULF alliance"s candidates in Jaffna District at the 1989 parliamentary election.
He was elected and entered Parliament. On 20 October 2001 the All Ceylon Tamil Congress, EPRLF, Tamil Eelam Liberation Organization and Tamil United Liberation Front formed the Tamil National Alliance (TNA).
He contested the 2001 parliamentary election as one of the TNA"s candidates in Jaffna District but failed to get elected. Premachandran contested the 2004 parliamentary election as one of the TNA"s candidates in Jaffna District.
He was elected and re-entered Parliament.
He was re-elected at the 2010 parliamentary election. He failed to get re-elected at the 2015 parliamentary election after coming seventh amongst the TNA candidates.
Premachandran got involved in the Sri Lankan Tamil nationalism movement whilst at school and in 1976, whilst in London, he joined the Eelam Revolutionary Organisation of Students (EROS).
He is the current leader of the Eelam People"s Revolutionary Liberation Front (EPRLF), a member of the Tamil National Alliance (TNA). He took on the nom de guerre Suresh and was a member of the EPRLF"s central committee and politbureau.