[2] After the Leonora sugar workers' strike in 1939, membership began to increase significantly, passing the 20,000 mark in 1943, making it the largest union in the country.
[1] In 1945 Cheddi Jagan became its treasurer, but he left a year later after several clashes with the moderate leadership over policy,[2] including the union's pro-employer attitude.
[5] During a strike in the same month, the MPCA urged strikers to return to work, claiming their demands would be discussed with the SPA.
[8] From 1960, the union's leaders supported the new United Force party led by Peter d'Aguiar.
Following a strike in 1964, Prime Minister Jagan asked Governor Ralph Grey to undertake a poll.