Upon completion of his studies, he sought employment as a clerk in the Ceylon railway department, but later turned his attention to journalism.

He was prominent in forming the "Young Lanka League" on 2 March 1915 along with barrister C. H. Z. Fernando, Edwin Wijeyeratne, A. P. Thambayah and Valantine Perera, later joined by Victor Corea, a lawyer from Chilaw in the fight against colonialism.

Jayatilaka, D. S. Senanayake, and many others including C. A. Hewavitharana and Henry Pedris, who was shot under martial law for crimes he did not commit.

Gunasinha himself joined the movement, breaking rocks by hand between 8:00 AM and 4:30 PM with a recess time of half-an-hour for lunch.

Reaching the workers, educating them about their rights and privileges, holding propaganda meetings he swelled the membership of the CLU.

The Strike was a great success, and a Commission appointed by the British Governor Sir William Henry Manning, recommended a 20% increase in Salaries and Casual & Sick leave grants.

Gunasinha next led a strike of the Colombo Harbour workers in February 1927 demanding a wage increase of 50 cts (from Rs.

The Late President J.R. Jayewardene, who was then a student, joined the many other helpers to transport the crowds of people who boycotted travelling in Tarm Cars.

As the strike progressed, due to Police harassment of the strikers, it spread to other institutions and demonstrations followed.

The demonstrations started from Price Park and the rally was held ultimately at the Galle Face Green.

May Day was declared public holiday by the Mahajana Eksath Peramuna Government led by Prime Minister S. W. R. D. Bandaranaike, in 1956.

Gunasinha's political career marked the formation of the Ceylon Labour Party in October 1928, with himself as president, and Proctor Marshall Perera as secretary, and Messrs. C.E.

Corea, C. H. Z. Fernando, C. W. W. Kannangara, George E. de Silva and late President Ranasinghe Premadasa, who was a very eloquent speaker, in the Committee.

[1] Gunasinha accompanied by C. H. Z. Fernando represented Ceylon at the British Empire Labour Conference held in London in 1928.

[2] The Labour Party campaigned for the unrestricted granting of Universal Adult Suffrage from the Donoughmore Commission.

[1][2] He was elected to the State Council of Ceylon in 1931, on the Labour Party ticket as member for Colombo Central Electoral District and was re-elected in 1936 and served till 1942 and was succeeded by M. C. M. Kaleel.

This national hero died on 1 August 1967, and was carried through the streets of Colombo by workers, to the cemetery, where he was laid to rest in peace.

Gunasinha's devoted disciple and follower, the President Ranasinghe Premadasa, converted Price Park and the environment in Pettah, as "Gunasinhapura" as a tribute to this leader of the workers.

As a mark of honour; his statue has been erected at the entrance to Gunasinha, depicting him with a hammer in hand breaking rock stones for Civil Disobedience in not paying Poll Tax.