[6][7] The LSSP played a major role in a wave of strikes in 1939/40 and consequently it was proscribed in 1940 and its leaders Colvin R. de Silva, Philip Gunawardena, N. M. Perera and Edmund Samarakkody arrested in June 1940.

[7][8][9] However, Anthony Pillai, Caroline and her brother Robert Gunawardena continued to organise strikes by bus, harbour and granary workers during 1940-41.

[8][9] In July 1942 the bulk of LSSP members, including Anthony Pillai, clandestinely crossed over to India in fishing boats.

[4][5] Whilst most went to Bombay, Anthony Pillai and a few other LSSP members went to Madurai where they joined the Bolshevik–Leninist Party of India, Ceylon and Burma (BLPI).

[1] Anthony Pillai, his family and several Ceylonese BLPI members, including some who had fled Bombay, were living in a large, two-storey house at the Venus Colony in Teynampe.

[4][5] Anthony Pillai and other BLPI members then sought refuge in an outhouse behind Ambi’s Café but in 1944 they were recognised.

[4][5] The police arrested everyone at the refuge and Anthony Pillai and another Ceylonese BLPI member were sentenced to two years’ rigorous imprisonment for "possessing seditious literature".

[2][4][5] However, shortly afterwards the family returned to India when Anthony Pillai was invited back to take over the leadership of the Madras Labour Union (MLU).

[4][5] Tens of thousands of workers took part in hartals and demonstrations demanding the release of Anthony Pillai and other union leaders.

[4][5] The government, fearing that workers may try to free Anthony Pillai, transferred him to a prison in remote Andhra.

[2] He was a member of the All India Trade Union Congress' general council and the Workers' United Front's executive committee in 1947.