Born on October 8th 1908 in the village of Kellaki, Limassol District, in Cyprus, Papaioannou worked as a miner, and then as a manual worker in the port of Piraeus. He moved to London in the early 1930s and became an active member of the British Communist Party. During this period he was jailed for three months arising from anti-fascist activities in Britain.
He became a founding member of the Association of Cypriot Affairs which sought the expulsion of the British from Cyprus.
In 1936, he was part of a contingent of 60 Cypriots who volunteered to fight in the Spanish Civil War as part of the International Brigades. 15 of them died and Papaioannou was injured, being repatriated to London, where he volunteered for the city’s air defence activity during the Second World War and worked as a milkman for a long time.
The Communist Party’s base amongst Cypriots began to grew strongly at this time and the Party maintained this through the Cypriot Advisory Committee, which Papaioannou participated in. The London Cypriot community also published its own Greek Language weekly, Vema, for many years, which was unambiguously Communist.
In 1945, Papaioannou was asked by the Cypriot Progressive Party of Working People (AKEL), the local communist and workers’ party, to return to Cyprus, where he remained until the end of his life.
In short order, he became the editor of the Party’s newspaper, then its General Secretary, a position he held for 40 years until his death. In 1960, following the independence of Cyprus from the British Empire, he was elected to the nation’s new parliament in which he served for 28 consecutive years up until his death on April 10th 1988.